An immunoproteomic approach revealed antigenic proteins enhancing serodiagnosis performance of bird fancier's lung

Sensitization to avian and fungal proteins in different work environments

INTRODUCTION

Hypersensitivity pneumonitis (HP) is usually caused by the inhalation of avian and fungal proteins. The present study assesses a cohort of Urban Pest Surveillance and Control Service (UPSCS) workers with high exposure to avian and fungal antigens, in order to identify their degree of sensitization and the potential risk of developing HP.

METHODS

Workers were divided according to their work activity into Nest pruners (Group 1) and Others (Group 2). All individuals underwent a medical interview, pulmonary function tests and the determination of specific IgG antibodies. Antigenic proteins of pigeon sera were analysed using two-dimensional immunoblotting. Proteins of interest were sequenced by liquid-chromatography-mass spectrometry (LC-MS).

RESULTS

101 workers were recruited (76 men, average age: 42 yrs); (Group 1 = 41, Group 2 = 60). Up to 30% of the study population exhibited increased levels of IgGs to pigeon, small parrot and parrot, and up to 60% showed high levels of Aspergillus and Penicillium IgGs. In Group 1, specific parakeet and Mucor IgGs were higher (p = 0.044 and 0.003 respectively) while DLCO/VA% were lower (p = 0.008) than in Group 2. Two-dimensional immunoblotting showed protein bands of 20-30 KDa recognized by HP patients but not by workers. LC-MS analysis identified Ig Lambda chain and Apolipoprotein A-I as candidate proteins for distinguishing HP patients from exposed workers.

CONCLUSIONS

Two pigeon proteins were identified that may play a role in the development of pathological differences between HP patients and exposed workers. DLCO/VA may have a predictive value in the development of HP disease.

Bird fancier's lung serodiagnosis by automated r-IgLL1 ELISA

CONTEXT

Bird fancier's lung (BFL) is the most prevalent form of hypersensitivity pneumonitis (HP) worldwide. The current techniques used for the serological diagnosis of BFL all use crude extracts from feathers, droppings, and blooms as test antigens, which is associated with a lack of standardization and variability of the results. An antigenic protein, immunoglobulin lambda-like polypeptide-1 (IgLL1), isolated from pigeon droppings, was recently identified to be associated with BFL. We used genetic engineering to produce IgLL1 as a recombinant antigen.

AIM

We aimed to prospectively validate the use of an automated ELISA based on recombinant IgLL1 protein (r-IgLL1) as the test antigen for the serological diagnosis of BFL.

METHODS

Immunoprecipitation (IP) techniques (immunodiffusion (ID), immunoelectrophoresis (IEP)) and ELISA using r-IgLL1 were performed concomitantly over 10 months on 634 sera from patients with a BFL serodiagnosis request. Questionnaires were sent to obtain details on the avian exposure, clinical data, and final diagnosis. Concordance, sensitivity (Se), and specificity (Sp) of the two techniques were compared.

RESULTS

In total, 72 completed questionnaires were returned with 18 cases of BFL diagnosed and 54 of non-BFL. The concordance between the ELISA and ID+IEP precipitation techniques was 71%. The combination of immunoprecipitation techniques showed a Se of 78% and a Sp of 67%. The ELISA using r-IgLL1 showed a Se of 89% and a Sp of 91%. The automated r-IgLL1 ELISA test is sufficiently efficient to be used alone for the diagnosis of patients exposed solely to Columbidae. In cases of other avian exposure, the Se and Sp of the r-IgLL1 ELISA used for screening combined with the immunodiffusion test for confirmation were 89% and 93%, respectively.

CONCLUSIONS

The automated ELISA using r-IgLL1 is a promising tool for BFL serodiagnosis. Replacing immunodiffusion by the automated ELISA using r-IgLL1 as a screening technique will be the basis of our future strategy for BFL serodiagnosis.

A rapid test for the environmental detection of pigeon antigen

INTRODUCTION

Avoidance of inhaled bird antigens is essential to prevent hypersensitivity pneumonitis disease progression. The aim of the present study was to develop a sandwich enzyme link immunoassay (ELISA) and an immunochromatographic test (ICT) and compare their ability to detect pigeon antigens in environmental samples.

METHODS

An amplified sandwich ELISA using pigeon serum as a calibration standard and a ICT using gold-labeled anti-pigeon serum antibodies for the rapid detection of pigeon antigens in environmental samples were developed. Twenty-two different airborne samples were collected and analysed using both methods. Strip density values obtained with ICT were calculated and compared with the concentrations determined by the ELISA method for pigeon antigens. Strips results were also visually analysed by five independent evaluators.

RESULTS

The ELISA method to quantify pigeon antigen had a broader range (58.4 and 10,112.2 ng/ml), compared to the ICT assay (420 to 3360 ng/ml). A kappa index of 0.736 (p < 0.0001) was obtained between the observers evaluating the ICT strips. The results of the ELISA and the relative density of the ICT showed a highly significant correlation (rs:0.935; p < 0.0001). Bland-Altman plot also confirmed excellent agreement between the two methods (mean difference: -1.626; p < 0.0001).

CONCLUSIONS

Since there was a good correlation between both assays, we can conclude that the rapid and simple ICT assay is a good and valid alternative, which does not require expensive equipment, for the validated ELISA technique.

Development of a Diagnostic Biosensor Method of Hypersensitivity Pneumonitis towards a Point-of-Care Biosensor

In spite of a current increasing trend in the development of miniaturized, standalone point-of-care (PoC) biosensing platforms in the literature, the actual implementation of such systems in the field is far from being a reality although deeply needed. In the particular case of the population screenings for local or regional diseases related to specific pathogens, the diagnosis of the presence of specific antibodies could drastically modify therapies and even the organization of public policies. The aim of this work was to develop a fast, cost-effective detection method based on the manipulation of functionalized magnetic beads for an efficient diagnosis of hypersensitivity pneumonitis (HP), looking for the presence of anti-pigeon antigen antibodies (APAA) in a patient’s serum. We presented a Diagnostic Biosensor Method (DBM) in detail, with validation by comparison with a traditional high-throughput platform (ELISA assay). We also demonstrated that it was compatible with a microfluidic chip that could be eventually incorporated into a PoC for easy and broad deployment using portable optical detectors. After standardization of the different reaction steps, we constructed and validated a plastic chip that could easily be scaled to high-volume manufacturing in the future. The solution proved comparable to conventional ELISA assays traditionally performed by the clinicians in their laboratory and should be compatible with other antibody detection directly from patient samples.

Diagnosis and Evaluation of Hypersensitivity Pneumonitis: CHEST Guideline and Expert Panel Report

BACKGROUND

The purpose of this analysis is to provide evidence-based and consensus-derived guidance for clinicians to improve individual diagnostic decision-making for hypersensitivity pneumonitis (HP) and decrease diagnostic practice variability.

STUDY DESIGN AND METHODS

Approved panelists developed key questions regarding the diagnosis of HP using the PICO (Population, Intervention, Comparator, Outcome) format. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion, and vetted evaluation tools were used to assess the quality of included studies, to extract data, and to grade the level of evidence supporting each recommendation or statement. The quality of the evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Graded recommendations and ungraded consensus-based statements were drafted and voted on using a modified Delphi technique to achieve consensus. A diagnostic algorithm is provided, using supporting data from the recommendations where possible, along with expert consensus to help physicians gauge the probability of HP.

RESULTS

The systematic review of the literature based on 14 PICO questions resulted in 14 key action statements: 12 evidence-based, graded recommendations and 2 ungraded consensus-based statements. All evidence was of very low quality.

INTERPRETATION

Diagnosis of HP should employ a patient-centered approach and include a multidisciplinary assessment that incorporates the environmental and occupational exposure history and CT pattern to establish diagnostic confidence prior to considering BAL and/or lung biopsy. Criteria are presented to facilitate diagnosis of HP. Additional research is needed on the performance characteristics and generalizability of exposure assessment tools and traditional and new diagnostic tests in modifying clinical decision-making for HP, particularly among those with a provisional diagnosis.

Executive Summary: Diagnosis and Evaluation of Hypersensitivity Pneumonitis: CHEST Guideline and Expert Panel Report

BACKGROUND

The purpose of this summary is to provide a synopsis of evidence-based and consensus-derived guidance for clinicians to improve individual diagnostic decision-making for hypersensitivity pneumonitis (HP) and decrease diagnostic practice variability.

STUDY DESIGN AND METHODS

Approved panelists developed key questions regarding the diagnosis of HP using the PICO (Population, Intervention, Comparator, and Outcome) format. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion and vetted evaluation tools were used to assess the quality of included studies, to extract data, and to grade the level of evidence supporting each recommendation or statement. The quality of the evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Graded recommendations and ungraded consensus-based statements were drafted and voted on using a modified Delphi technique to achieve consensus.

RESULTS

The systematic review of the literature based on 14 PICO questions resulted in 14 key action statements: 12 evidence-based, graded recommendations, and 2 ungraded consensus-based statements. All evidence was of very low quality.

INTERPRETATION

Diagnosis of HP should employ a patient-centered approach and include a multidisciplinary assessment that incorporates the environmental and occupational exposure history and CT pattern to establish diagnostic confidence prior to considering BAL and/or lung biopsy. Additional research is needed on the performance characteristics and generalizability of exposure assessment tools and traditional and new diagnostic tests in modifying clinical decision-making for HP, particularly among those with a provisional diagnosis.

Pilot Study Using Recombinant Antigens r-PROE and r-IGLL1 for the Serodiagnosis of Feather Duvet Lung

BACKGROUND

Feather duvet lung (FDL) is an underestimated form of acute and chronic hypersensitivity pneumonitis. Serological tests for FDL need to be validated. We investigated the ability of recombinant pigeon Proproteinase E (r-PROE) and Immunoglobulin-lambda-like-polypeptide-1 (r-IGLL1) proteins to support the serological diagnosis of FDL, and propose them as a serological tool for clinicians to differentiate cases from FDL and Bird fancier's lung (BFL).

METHODS

Specific IgG antibodies against r-PROE and r-IGLL1, analyzed with ELISA, were measured in patients diagnosed with FDL (n=31), BFL (n=15) controls exposed (n=15) and unexposed to feathers (n=15).

RESULTS

The sensitivity and specificity of the r-PROE ELISA for the serological diagnosis of FDL cases versus exposed and unexposed controls were 74.2% and 86.7% respectively, with an index threshold of 0.5 (AUC: 0.89). In addition, this serological test was effective to support the serological diagnosis of FDL and BFL cases with significantly different thresholds. The r-IGLL1 ELISA was only effective for the serological diagnosis of BFL. Also, these two serological tests were useful for the diagnosis of both chronic and acute forms.

CONCLUSIONS

The new diagnostic test for FDL using r-PROE protein should help to detect overt and hidden cases of FDL. The combination of both test will help the clinician in distinguish between the etiology of birds or feathers duvet.

The association between fungi exposure and hypersensitivity pneumonitis: a systematic review

A systematic review of published studies focused on the association between hypersensitivity pneumonitis (HP) and fungi exposure was conducted on PubMed, following PRISMA guidelines for systematic reviews. A total of 14 studies met the inclusion criteria but only 6 of these studies were eligible, as the remaining 8 represented case reports that were separately included for further discussion. HP is an interstitial lung disease (ILD) characterized by a hypersensitization response to inhalable antigens and represents 1.5% to 12% of all ILD in the European population. Several fungi species that populate the indoor environment have been associated with the incidence of HP upon cumulative exposure, with Penicillium spp and Aspergillus spp being the fungi species most frequently associated with the onset of disease. Although some studies have shown that avoiding exposure to causative HP fungi tends to improve patients’ symptoms, other studies were unable to identify the source of sensitization. More microbial exposure studies are needed to properly estimate the risk of HP development in the built environment.

Exposure Assessment Tools for Hypersensitivity Pneumonitis. An Official American Thoracic Society Workshop Report

This report is based on proceedings from the Exposure Assessment Tools for Hypersensitivity Pneumonitis (HP) Workshop, sponsored by the American Thoracic Society, that took place on May 18, 2019, in Dallas, Texas. The workshop was initiated by members from the Environmental, Occupational, and Population Health and Clinical Problems Assemblies of the American Thoracic Society. Participants included international experts from pulmonary medicine, occupational medicine, radiology, pathology, and exposure science. The meeting objectives were to 1) define currently available tools for exposure assessment in evaluation of HP, 2) describe the evidence base supporting the role for these exposure assessment tools in HP evaluation, 3) identify limitations and barriers to each tool's implementation in clinical practice, 4) determine which exposure assessment tools demonstrate the best performance characteristics and applicability, and 5) identify research needs for improving exposure assessment tools for HP. Specific discussion topics included history-taking and exposure questionnaires, antigen avoidance, environmental assessment, specific inhalational challenge, serum-specific IgG testing, skin testing, lymphocyte proliferation testing, and a multidisciplinary team approach. Priorities for research in this area were identified.

Diagnosis of occupational hypersensitivity pneumonitis

PURPOSE OF REVIEW

To discuss the diagnostic methods currently used in the study of patients with hypersensitivity pneumonitis, with special emphasis on the most recent contributions published in the medical literature regarding the diagnosis of occupational hypersensitivity pneumonitis (OHP). This review presents an update of the use of these diagnostic tests, a controversial issue among experts.

RECENT FINDINGS

In spite of the multiple attempts at systematization and the publication of expert consensus statements, standardizing and diagnostic methods and criteria remain particularly difficult. As a result, centers tend to rely on their own experience and establish diagnosis by consensus among their multidisciplinary teams. Though recommendable in many ways, this method presents significant limitations.

SUMMARY

Diagnosis of OHP should be made with a thorough clinical history of the symptoms and clinical signs as well as a meticulous review, if possible by an expert, of possible exposures in the working environment; a meticulous physical examination; high-resolution computed tomography of the thorax; serum determination of specific immunoglobuline Gs; bronchoalveolar lavage and possibly cryobiopsy; fungal culture; and, when appropriate, a specific inhalation challenge test with the suspected antigen.

Diagnostic accuracy of specific IgG antibodies for bird fancier's lung: a systematic review and meta-analysis

Background

Serologic assays for specific immunoglobulin G (IgG) antibodies are available for diagnosing the condition of bird fancier's lung, however, their usefulness is controversial. This systematic review was aimed at investigating the diagnostic accuracy of specific IgG antibodies used for avian antigens.

Methods

Medline, Embase, the Cochrane Library, the International Clinical Trials Registry Platform, and the Web of Science were searched for studies performed to evaluate the diagnostic accuracy of the Ouchterlony method, enzyme-linked immunosorbent assays (ELISAs), electrosyneresis, and ImmunoCAP assays for diagnosing bird fancier's lung. Nine articles were included in the meta-analysis. The pooled sensitivity and specificity were summarized using a bivariate mixed-effects model, and a hierarchical summary receiver operating characteristic curve was rendered to determine the diagnostic accuracy of the antibodies.

Results

The pooled sensitivities and specificities of each specific IgG antibody were 82.9% (95% confidence interval, 71.1-90.5%) and 93.0% (95% confidence interval, 74.4-98.4%) for the Ouchterlony method, 92.5% (95% confidence interval, 71.3-98.4%) and 90.8% (95% confidence interval, 72.1-97.4%) for ELISAs, 90.0% (95% confidence interval, 55.5-99.7%) and 84.6% (95% confidence interval, 73.5-92.4%) for the electrosyneresis method, and 43.5% (95% confidence interval, 35.3-52.1%) and 100% (95% confidence interval, 0-100%) for ImmunoCAP assays. The overall quality of the collective evidence was low, primarily due to the high risk of bias, indirectness, and imprecision of the included studies.

Conclusions

The Ouchterlony method demonstrated high specificity, the ELISA method showed high sensitivity, and the diagnostic utilities of electrosyneresis and ImmunoCAP assay testing remain unclear.

[Hypersensitivity pneumonitis in children]

Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by an immune response to a variety of antigens to which patients have been previously sensitised. It can occur at any age. In children, it is a rare disease, probably under-diagnosed, with an estimated prevalence of 4 per million. The paediatric forms are not really different from those of adults but present some particularities. Avian exposure is by far the most frequent cause of HP, accounting for nearly two-thirds of cases. Although there is no current recommendation for the diagnosis of HP, it is commonly considered that the diagnosis can be made with confidence on the combination of (1) compatible respiratory symptoms, (2) exposure to a known offending antigen, (3) lymphocytic alveolitis, (4) decreased transfer factor for carbon monoxide or hypoxia on exertion and (5) compatible radiologic features. The treatment is based on antigen avoidance that must be complete and definitive. Corticosteroids can be necessary in severe forms. The prognosis of HP in children is better than in adults, with a full clinical and functional recovery in the majority of cases after complete antigenic withdrawal.

Hypersensitivity pneumonitis: A new strategy for serodiagnosis and environmental surveys

We propose a strategy for serodiagnosis of hypersensitivity pneumonitis (HP): 1) question patients about their private or occupational activity, or visit him on site; 2) select panels of six somatic specific antigens appropriate for each type of exposure; 3) and use ELISA to test concomitantly two recombinant antigens highly specific to Farmer's lung, Metalworking-fluid HP, and for Bird fancier's lung. The serodiagnosis provides an immunological argument that may complete radiological, functional lung exploration and clinical features; 4) If the serodiagnosis is negative but the suspicion of HP is strong, a microbial analysis of the patient's specific exposure is conducted; 5) "A la carte" antigens are produced from the microorganisms isolated in the patient's environment sample and tested; 6) Finally, the patient may be asked to undergo a specific inhalation challenge with the offending antigens in a safety cabin, or to avoid his usual environment for a few days.

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.

Current and emerging techniques for the diagnosis of hypersensitivity pneumonitis

INTRODUCTION

Hypersensitivity pneumonitis (HP) is the result of an immunologically induced inflammation of the lung parenchyma in response to inhalation exposure to a large variety of antigens in genetically susceptible individuals. HP shares clinical and radiological features with other acute and chronic interstitial lung diseases and is sometimes difficult to diagnose if exposure to an antigenic agent is not detected. Several classifications and diagnostic criteria have been proposed but are not currently recommended by guidelines from any scientific society. However, advances have been made over the past ten years in improving the diagnosis of HP. Areas covered: This article will provide a summary of the different classification and diagnostic criteria proposed in acute and chronic forms of HP. In addition, we review current diagnostic procedures including antigen detection, high resolution computed tomography, histopathology and provide an overview of emerging techniques. Expert commentary: Important changes are occurring in the field of HP and knowledge of the disease will likely progress enormously in the coming 5 to 10 years as many techniques continue to be developed, including genomic signature and diagnostic biomarkers.