Masks of hypersensitivity pneumonitis in children

Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis, is the most common interstitial lung disease in children, but remains rarely recognized in the pediatric population. Early recognition of triggering factors and a high index of suspicion of HP could lead to timely diagnosis and individualized treatment. This study aimed to present four clinical cases of HP reported between 2012 and 2022 in Lithuania to improve the suspicion of the disease in children.

Co-modulation of T cells and B cells enhances the inhibition of inflammation in experimental hypersensitivity pneumonitis

Background

Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by antigen-triggered neutrophilic exacerbations. Although CD4⁺ T cells are sufficient for HP pathogenesis, this never translated into efficient T cell-specific therapies. Increasing evidence shows that B cells also play decisive roles in HP. Here, we aimed to further define the respective contributions of B and T cells in subacute experimental HP.

Methods

Mice were subjected to a protocol of subacute exposure to the archaeon Methanosphaera stadmanae to induce experimental HP. Using models of adoptive transfers of B cells and T cells in Rag1-deficient mice and of B cell-specific S1P₁ deletion, we assessed the importance of B cells in the development of HP by evaluating inflammation in bronchoalveolar lavage fluid. We also aimed to determine if injected antibodies targeting B and/or T cells could alleviate HP exacerbations using a therapeutic course of intervention.

Results

Even though B cells are not sufficient to induce HP, they strongly potentiate CD4⁺ T cell-induced HP‑associated neutrophilic inflammation in the airways. However, the reduction of 85% of lung B cells in mice with a CD19-driven S1P₁ deletion does not dampen HP inflammation, suggesting that lung B cells are not necessary in large numbers to sustain local inflammation. Finally, we found that injecting antibodies targeting B cells after experimental HP was induced does not dampen neutrophilic exacerbation. Yet, injection of antibodies directed against B cells and T cells yielded a potent 76% inhibition of neutrophilic accumulation in the lungs. This inhibition occurred despite partial, sometimes mild, depletion of B cells and T cells subsets.

Conclusions

Although B cells are required for maximal inflammation in subacute experimental HP, partial reduction of B cells fails to reduce HP-associated inflammation by itself. However, co-modulation of T cells and B cells yields enhanced inhibition of HP exacerbation caused by an antigenic rechallenge.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02200-9.

A cross sectional study on airborne inhalable microorganisms, endotoxin, and particles in pigeon coops - Risk assessment of exposure

Pigeon breeding is associated with symptoms of the airways. The aim of this study is to illuminate the bacteriological and toxicological characteristics of airborne dust in pigeon coops. Airborne dust was sampled in 31 urban pigeon coops with homing and fancy pigeons, and following the dust was characterized. In total 141 different bacterial species were identified using MALDI-TOF MS, and of these 11 species are classified in risk group 2. Of the cultivable bacteria, Staphylococcus equorum was present in the highest concentration. Microorganisms in the dust were able to form biofilm, and the amount correlated positively with the number of bacteria. Next generation sequencing showed 180 genera with Acinetobacter in highest reads. On average 999 ± 225 ZOTUs were observed per sample with a Shannon-Wiener biodiversity index of 6.17 ± 0.24. Of the identified species the following have previously been suggested as causative agents of extrinsic allergic alveolitis: Alcaligenes faecalis, Bacillus subtilis, Pantoea agglomerans, Sphingobacterium spiritivorum, Thermoactinomyces sp., and Streptomyces albus. Staphylococcus was present on particles with sizes between 1.1 and > 7.0 μm with a geometric mean diameter of particles on 4.7 ± 1.1 μm. Concentrations of airborne endotoxin and dust were elevated compared to references, and the geometric mean concentrations were 102 EU/m³ and 1.07 mg dust/m³, respectively. Upon exposure to the airborne dust human granulocytes produced Reactive Oxidative Species during the first 5 min, and then no further reaction was observed. The concentrations of bacteria in general, Staphylococcus spp., and endotoxin and biodiversity were associated significantly with season, temperature and/or relative humidity, but not with type or density of pigeons. The bacterial composition and biodiversity indices were not affected by type of pigeon. In conclusion, the exposure to bacteria and endotoxin in pigeon houses should not be neglected in the evaluation of causative agents of airways symptoms among pigeon breeders.

Management of Fibrotic Hypersensitivity Pneumonitis

Fibrotic hypersensitivity pneumonitis (fHP) is a chronic, often progressive fibrosing form of interstitial lung disease caused by inhaled antigenic exposures. fHP can lead to impaired respiratory function, reduced disease-related quality of life, and early mortality. Management of fHP should start with exposure remediation where possible, with systemic immunosuppression and antifibrotic therapy considered in patients with symptomatic or progressive disease. Nonpharmacologic and supportive management should be offered and, in cases of treatment-resistant, progressive illness, lung transplant should be considered.

[Girl with hypersensitivity pneumonitis. A case report]

BACKGROUND

Hypersensitivity pneumonitis entails several inflammatory lung diseases that preferentially affect the alveolar and perialveolar tissue. It is a very rare disease in children, with a complicated diagnosis due to the fact that antigen exposure usually goes unnoticed.

CASE REPORT

A 12-year-old girl with dry cough, dyspnea, wheezing, and tachypnea, with partial improvement after treatment with inhaled bronchodilators and corticoids. The spirometry showed a restrictive pattern and reduced lung diffusion capacity; in the CT scan, centrilobular ground-glass opacities were observed, and a lymphocyte count of CD4/CD8 of 2.46 (lymphocytosis) was obtained from the bronchoalveolar lavage. IgG positivity to bird feathers was obtained.

CONCLUSIONS

The treatment of hypersensitivity pneumonitis is based on avoiding exposure to the causative agent, which is determined by the prognosis; for which taking an extensive medical history is of paramount importance. Corticosteroids can be prescribed based on the clinical response, the pulmonary function, and the radiological improvement.

Insights on chronic hypersensitivity pneumonitis' treatment: Factors associated with a favourable response to azathioprine

BACKGROUND

The use of immunosuppressive and antifibrotic agents for the treatment of chronic hypersensitivity pneumonitis (CHP) appears promising, but there is still no evidence supporting the clinical decision regarding the implementation of each specific pharmacological strategy.

METHODS

Patients diagnosed with CHP and treated with azathioprine (AZA) were retrospectively selected from a single centre for Interstitial Lung Diseases. Baseline clinical data, as well as functional, imaging, bronchoalveolar lavage (BAL) and histology features were assessed. Longitudinal data on functional parameters were collected and comparatively analysed with patients' characteristics.

RESULTS

In this cohort of 80 patients, of those who reached 12 months of treatment, 78.3% presented a preserved forced vital capacity, with 59 being eligible to be classified as AZA responders (n = 36) or non-responders (n = 23). BAL lymphocytosis was associated with a favourable response to AZA treatment (OR 1.051; 95% CI 1.015-1.089), although it didn't identify all responders.

CONCLUSIONS

AZA revealed to be effective in disease stabilisation in most patients, while ineffective for a subset. BAL lymphocytosis appears as a potentially valuable strategy to identify AZA responders, although with limited accuracy. Further studies are needed to clarify other response markers to immunosuppressive agents, in order to optimize the therapeutic options for this condition.

Sooty bark disease of maples: the risk for hypersensitivity pneumonitis by fungal spores not only for woodman

In the middle of the twentieth century, the from North America sooty bark disease (SBD) of maples was first discovered in England and has spread in the last decades in Central Europe, in particular. The trigger of SBD is the mould fungus Cryptostroma (C.) corticale. The most common infested maple is the sycamore, Acer pseudoplatanus, a common tree in woods and parks. The disease is characterised by peeling of the outer layer of the bark and brownish-black spores under the peeled off bark. These spores can cause maple bark disease (MBD) in humans, a hypersensitivity pneumonitis (HP) with similar symptoms like COPD, allergic asthma, influenza or flu-like infections and interstitial pneumonia. Persons who have intensive respectively occupational contact with infested trees or wood, e.g., woodman, foresters, sawyers or paper mill workers, are at risk in particular. Since C. corticale favours hot summers and host trees weakened by drought, SBD will increasingly spread in the future due to ongoing climate change. Consequently, the risk of developing MBD will increase, too. As with all HPs, e.g., farmer's lung and pigeon breeder's disease, the diagnosis of MBD is intricate because it has no clear distinguishing characteristics compared to other interstitial lung diseases. Therefore, the establishment of consistent diagnosis guidelines is required. For correct diagnosis and successful therapy, multidisciplinary expertise including pulmonologists, radiologists, pathologists and occupational physicians is recommended. If MBD is diagnosed in time, the removal of the triggering fungus or the infested maple wood leads to complete recovery in most cases. Chronic HP can lead to lung fibrosis and a total loss of lung function culminating in death. HP and, thus, MBD, is a disease with a very high occupational amount. To avoid contact with spores of C. corticale, persons working on infested wood or trees have to wear personal protective equipment. To protect the public, areas with infested maples have to be cordoned off, and the trees should be removed. This is also for impeding further spreading of the spores.

Tobacco Worker's Lung: A Neglected Subtype of Hypersensitivity Pneumonitis

Tobacco worker's lung (TWL) is a type of hypersensitivity pneumonitis (HP) affecting workers exposed to tobacco leaves and molds in the humidified environment of the tobacco production industry. Limited epidemiological data point to a prevalence of TWL that is not negligible and probably underestimated. As in other types of HP, an acute vs. chronic presentation depends on the pattern of the exposure. Therefore, the clinical presentation can vary from an acute influenza-like syndrome, mostly self-limiting with the removal of the exposure, to an insidious onset of cough, exertional dyspnea, fatigue and weight loss in chronic presentations, where fibrotic changes may be observed. The main treatment strategy is the removal of the exposure to tobacco dust and molds, while the main aim of corticosteroid therapy is to reduce morbidity and prevent complications, namely the development of pulmonary fibrosis and permanent lung dysfunction. Despite the fact that TWL is quite well described, preventive measures are not usually adopted in the tobacco production industry. We present here a state of the art review of this neglected, preventable, but still prevalent and occupational-related subtype of HP.

Assessment and Management of Occupational Hypersensitivity Pneumonitis

The diagnosis and treatment of occupational hypersensitivity pneumonitis (OHP) remain complex and challenging in the absence of diagnostic gold standards or clinical guidelines. This review provides an update of the recent literature regarding the different presentations of OHP and the diagnostic yield and value of the diagnostic tests currently available, which include occupational and medical history, laboratory tests (serum-specific immunoglobulins, environmental sampling), imaging, bronchoalveolar lavage, transbronchial biopsy, transbronchial cryobiopsy, surgical lung biopsy, and specific inhalation challenges. These tools provide a precise differential diagnosis within the framework of interstitial lung diseases. However, among the chronic fibrotic forms, distinguishing OHP from sarcoidosis, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis remains a diagnostic challenge. Avoidance of exposure is pivotal for OHP management, whereas corticosteroids are fundamental in the pharmacological approach to this disease. In addition, studies describing the long-term benefits of immunosuppressive and antifibrotic agents have increased the use of these treatments in OHP.

Comorbidities and survival in patients with chronic hypersensitivity pneumonitis

Introduction

Chronic Hypersensitivity Pneumonitis (cHP) is a fibrotic interstitial lung disease (ILD) resulting from repeated exposure to an offending antigen. Prognostication in cHP remains challenging, and the relationship between comorbidities and survival has yet to be characterized. The aim of this study was to describe the relationship between comorbid conditions and survival in patients with cHP.

Methods

The prospective database from a tertiary referral centre for ILD was reviewed for patient-reported comorbidities, their frequency, and relationship with survival in cHP patients. Comorbidities were assessed by direct questioning of the patient at the baseline visit and by a standardized questionnaire for the diagnosis of interstitial lung diseases. During the follow-up examinations, patients were asked about newly diagnosed comorbidities.

Results

Two hundred eleven patients with cHP were identified (mean age 63 years, 53% male, mean FVC 73%), with mean follow-up of 32 months. The mean number of comorbidities was 3 (10% had 0, 59% 1–3 and 31% ≥4 comorbidities). Most frequent comorbidities groups were cardiovascular (65%) and respiratory (26%), most common comorbidities were hypertension (56%), gastro-esophageal reflux disease (GERD) (24%), diabetes (20%) and coronary heart disease (18%). In general, deceased patients had more comorbidities than survivors (p = 0.005), yet there was no association between the absolute number of comorbidities and survival. Pulmonary hypertension (30.8% versus 5.7%, p = 0.001;), diastolic dysfunction (26.9% versus 6.4%, p = 0.004) and cerebrovascular disease were more frequent in non-survivors (23.1% versus 7.6%, p = 0.026). Lung cancer was not observed, and neither GERD nor antacid drugs were associated with outcome (p = 0.357 and p = 0.961, respectively).

Conclusions

Comorbidities are common in cHP are associated with survival. Further work should determine whether interventions for these specific comorbidities can positively affect survival.

[A case of farmer's lung associated with allergic bronchopulmonary aspergillosis]

Hypersensitivity pneumonitis and allergic bronchopulmonary aspergillosis are two forms of lung disease with presumed distinct immunoallergic mechanisms. We report the observation of a 38-year-old French farmer who, for one month, had fever and dyspnoea resistant to antibiotic therapy. A diagnosis of farmer's lung, and allergic bronchopulmonary aspergillosis was made on clinical, biological, functional and radiological evidence and according to the criteria established. The evolution was favorable with antigenic eviction and corticosteroid therapy. This observation is to our knowledge the 5^th case that describes the association of hypersensitivity pneumonitis and allergic bronchopulmonary aspergillosis. It suggests the existence of risk factors and immunoallergic mechanisms common to both diseases and discusses the hypothesis that the same antigen(s) is (are) responsible for them.

Comparative survival analysis between idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis

INTRODUCTION

Chronic hypersensitivity pneumonitis (CHP) is an interstitial lung disease with limited treatment response and bad prognosis. Sometimes it is indistinguishable from idiopathic pulmonary fibrosis (IPF) becoming one of the main differential diagnosis. The aim of our study is to compare survival and functional decline between these two entities.

METHODS

Survival and functional decline more than 10% in FVC were compared using Kaplan Meier (KM) method between patients with CHP and IPF. Cox proportional hazard analysis was used to identify independent predictors of survival and functional decline.

RESULTS

146 patients were included, 54 with CHP and 92 with IPF. KM rate for 2 years survival was 0.71 (CI 95% 0,6-0,8) for CHP group and 0,83 (CI 95% 0,66 - 0,92) for IPF (p=0,027). Nevertheless this difference disappeared using Cox proportional hazard analysis, the adjusted HR for survival among CHP patients was 0,53 (CI 95% 0,25-1,15) (p=0,11). There was no difference in functional evolution between the two groups. KM rate for a decline more than or equal to 10% was 0,64 for CHP (CI 95% 0,43-0,79) and 0,78 for IPF (IC 95% 0,6-0,88) (p=0,22). This observation did not change after using Cox proportional hazard analysis.

CONCLUSIONS

Our study shows that both IPF and CHP are fibrosing interstitial diseases with a similar evolution and survival. It might be possible that therapeutic approach in patients with CHP should change in the light of these observations.

Bronchoalveolar lavage cell profiles and proteins concentrations can be used to phenotype extrinsic allergic alveolitis patients

Background

Extrinsic allergic alveolitis (EAA) patients form heterogenous group with different clinical manifestation and different prognosis. We aimed to determine how to phenotype distinct EAA subgroups. Predictive role of the bronchoalveolar lavage fluid (BALF) IL-4Rα concentration at the time of diagnosis with regard to the clinical behavior in EAA patients was studied.

Methods

Concentrations of MMP-7, IL-4Rα, TNF-α, and PAR-2 were measured in the BALF od 71 EAA patients at the time of diagnosis. Lung functions and outcome data were assessed at 12 months after the diagnosis. Correlations between the BALF protein concentration, cell profile, lung functions and patient outcome were determined.

Results

We found positive correlations between BALF IL-4Rα concentration and BALF eosinophils (p = 0,006), negative correlation between IL-4Rα BALF concentration and diffusing capacity (DLco) (p = 0,003), negative correlation between IL-4Rα BALF concentration and forced vital capacity (FVC) (p = 0,004) and negative correlation between IL-4Rα concentration and BALF lymphocytes (p = 0,04). The BALF concentration of IL-4Rα was significantly higher in acute exacerbation patients (p = 0,0032) and in patients progressing despite corticosteroid treatment (p = 0,04). We observed a positive correlation between MMP-7 BALF concentration and the BALF lymphocytes (p = 0.05), negative correlation between the PAR-2 BALF concentration and DLco (p = 0.04) and a negative correlation between the BALF TNF-α concentration and DLco (p = 0.03).

Conclusions

Specific subgroup of EAA patients with more severe functional impact, distinct BALF cell profile and higher IL-4Rα BALF concentration can be differentiated. Correlations between the BALF concentrations of PAR-2, MMP-7 and TNF-α with clinical parameters may reflect the role of inflammation in the pathogenesis of EAA.

Protein antigen of bird-related hypersensitivity pneumonitis in pigeon serum and dropping

BACKGROUND

Avian antigen is a common cause of hypersensitivity pneumonitis (HP). Inhalation challenge with pigeon serum and pigeon dropping extract (PDE) elicits a hypersensitivity reaction in patients with bird-related hypersensitivity pneumonitis (BRHP), but the antigenic components in these materials have yet to be fully elucidated.

METHOD

Pigeon serum, pigeon intestine homogenates, and PDE were immunoblotted with serum samples from 8 patients with BRHP, 2 patients with summer-type HP, 2 patients with humidifier lung, and 3 healthy volunteers. Among the protein spots found in both pigeon serum and PDE, those that reacted with sera from BRHP patients were identified by mass spectrometry. Immunoassays using recombinant protein were performed to confirm the antigenicity of the identified protein. Cytokine production by peripheral blood mononuclear cells (PBMCs) stimulated with recombinant protein was also assessed.

RESULTS

Immunoglobulin lambda-like polypeptide-1 (IGLL-1) was identified from all spots on 2-DE immunoblots of both pigeon serum and PDE. The BRHP patients exhibited higher levels of serum IgG antibody against the recombinant IGLL-1 (rIGLL-1) compared to the control subjects, as well as a stronger PBMCs proliferative response to rIGLL-1. Cytokine production by PBMCs from BRHP patients after rIGLL-1 exposure indicated that the protein could induce Th1 prone immune responses: an increase in TNF-α and an absence of elevated IL-10 production.

CONCLUSIONS

Pigeon IGLL-1 was identified as the BRHP antigen present in both pigeon serum and PDE.

Hypersensitivity Pneumonitis in a Housewife Exposed to Aspergillus flavus in Poor Living Conditions: A Case Report

Hypersensitivity Pneumonitis (HP) or Extrinsic Allergic Alveolitis (EAA) is a disease resulting from immunologically induced inflammation in response to inhalation of a wide variety of airborne allergens. The condition develops mainly in non atopic individuals sensitized to organic dust due to repeated exposures. It is a relatively rare disease constituting upto 2% of interstitial lung diseases. Knowledge of classical High Resolution Computed Tomography (HRCT) of lung findings aid in early diagnosis. We report a case of subacute hypersensitivity pneumonitis in a housewife who despite being symptomatic remained undiagnosed for two years. She showed a good response to therapy, but soon relapsed. Visit to her home revealed that she lived in a damp house full of moldy walls.

Mycobacterium phocaicum and Mycobacterium avium-intracellulare in a patient with hot tub lung

A 77-year-old woman who used her spa pool at least twice a day to relieve pain from osteoarthritis, developed progressive breathlessness, impaired pulmonary function, and radiographic changes consistent with hypersensitivity pneumonitis-like lung disease. M ycobacterium avium-intracellulare complex (MAC) was cultured from bronchoalveolar lavage fluid. Transbronchial biopsies revealed non-necrotizing granulomatous inflammation. Sputum and spa pool water cultured M ycobacterium phocaicum but not MAC. She stopped using the spa pool and was treated with oral prednisone, which led to symptomatic, pulmonary function, and radiographic improvement. This is the first case of hypersensitivity pneumonitis-like granulomatous lung disease associated with exposure to M . phocaicum in spa pool water.

Nationwide epidemiological survey of chronic hypersensitivity pneumonitis in Japan

BACKGROUND

In 1999, a Japanese epidemiological survey of chronic hypersensitivity pneumonitis (HP) showed that summer-type HP was the most prevalent variant of the disease. The number of reported cases of chronic HP has recently been increasing, and the clinical features of the disease seem to have changed. We conducted another nationwide epidemiological survey of chronic HP in Japan to determine better estimates of the frequency and clinical features of the disease.

METHODS

A questionnaire was sent to qualified hospitals throughout Japan, and data on cases of chronic HP diagnosed between 2000 and 2009 were collected.

RESULTS

In total, 222 cases of chronic HP from 22 hospitals were studied. Disease subtypes included bird-related HP (n=134), summer-type HP (n=33), home-related HP (n=25), farmer's lung (n=4), isocyanate-induced HP (n=3), and other types (n=23). The median proportion of lymphocytes in bronchoalveolar lavage fluid was high (24.5%). The primary findings of computed tomography of the chest were ground-glass attenuation and interlobular septal thickening. Centrilobular fibrosis was the major pathological finding on examination of surgical lung biopsy specimens from 93 patients. The median survival time was 83 months.

CONCLUSIONS

The proportion of bird-related HP was higher than that in the previous epidemiological survey, and the proportions of isocyanate-induced HP and farmer's lung were lower. A crucial step in diagnosing chronic HP is to thoroughly explore the possibility of antigen exposure.

Hypersensitivity Pneumonitis: Essential Radiologic and Pathologic Findings

Hypersensitivity pneumonitis is a diffuse, granulomatous interstitial lung disease caused by repeated exposure to a wide spectrum of environmental antigens. Clinical, radiologic, and histologic findings are quite variable and mimic many other diseases; therefore, diagnosis depends on a constellation of findings rather than a single defining feature. High-resolution computed tomography (HRCT) plays a critical role in this setting. The presence of centrilobular nodules, multifocal ground glass opacities, and evidence of air trapping in the expiratory phase of respiration is highly suggestive of hypersensitivity pneumonitis and can direct clinicians to the correct diagnosis. For the pathologist, typical HRCT findings not only corroborate the diagnosis of hypersensitivity pneumonitis when the characteristic triad of airway-centered chronic interstitial inflammation, interstitial poorly formed non-necrotizing granulomas, and organizing pneumonia is present on biopsy, but also improve diagnostic confidence in biopsies lacking components of the diagnostic histologic triad. Importantly, the presence of focal or unilateral imaging findings should prompt a careful search by the pathologist for an infectious etiology, thus avoiding errors in determining the significance of granulomas on biopsy. This article reviews the essential radiologic and pathologic findings in hypersensitivity pneumonitis, discusses the primary considerations in the differential diagnosis, and offers an approach to biopsy evaluation.