Risk factors associated with mortality in hypersensitivity pneumonitis: a meta-analysis.

BACKGROUND: Hypersensitivity pneumonitis (HP) related deaths have increased substantially in recent years. It is important to identify the risk factors of HP significantly associated with mortality to ensure close patient monitoring and assess disease progression. RESEARCH DESIGN AND METHODS: Extensive literature search was conducted in accordance with the PRISMA checklist. Literature search of PubMed, Embase, and Cochrane Library database between January 2009 and April 2021 using the terms 'hypersensitivity pneumonitis', 'hazard ratio', and 'mortality' identified 325 articles. A total of 22 independent original studies focusing on mortality of HP patients were assessed. RESULTS: This systematic review and meta-analysis suggests that increased age, male sex, honeycombing, and traction bronchiectasis patterns on high-resolution computed tomography (HRCT) images are the major mortality-related risk factors of patients with HP. In case of chronic HP, antigen exposure appeared to be an additional risk factor. CONCLUSIONS: The clinico-radiological risk factors of mortality identified for HP will enable effective and close monitoring of patients, prognostication, and guide toward appropriate management decisions. However, association between the type of antigen and mortality remains to be explored.

ITK independent development of Th17 responses during hypersensitivity pneumonitis driven lung inflammation.

T helper 17 (Th17) cells develop in response to T cell receptor signals (TCR) in the presence of specific environments, and produce the inflammatory cytokine IL17A. These cells have been implicated in a number of inflammatory diseases and represent a potential target for ameliorating such diseases. The kinase ITK, a critical regulator of TCR signals, has been shown to be required for the development of Th17 cells. However, we show here that lung inflammation induced by Saccharopolyspora rectivirgula (SR) induced Hypersensitivity pneumonitis (SR-HP) results in a neutrophil independent, and ITK independent Th17 responses, although ITK signals are required for γδ T cell production of IL17A. Transcriptomic analysis of resultant ITK independent Th17 cells suggest that the SR-HP-induced extrinsic inflammatory signals may override intrinsic T cell signals downstream of ITK to rescue Th17 responses in the absence of ITK. These findings suggest that the ability to pharmaceutically target ITK to suppress Th17 responses may be dependent on the type of inflammation.

Alternative Gene Expression by TOLLIP Variant Is Associated With Lung Function in Chronic Hypersensitivity Pneumonitis.

BACKGROUND: Chronic hypersensitivity pneumonitis (CHP) is a heterogeneous fibrotic interstitial pneumonia resulting from the immune response of susceptible individuals to inhaled antigens. Genetic predispositions have been suggested in CHP; however, the link between susceptibility genes and fibrotic progression has not been elucidated fully. Recent data suggest that variants in Toll-interacting protein gene (TOLLIP) are associated with lung diseases. RESEARCH QUESTION: Can TOLLIP variants be associated with any clinical features in patients with CHP? STUDY DESIGN AND METHODS: We genotyped rs5743899 and rs3750920 in TOLLIP and analyzed the association with clinical parameters in 101 patients with CHP (67 for the retrospective cohort and 34 for the prospective cohort). We evaluated the expression of TOLLIP and fibrogenic signals in affected lung tissues and periostin in sera. Furthermore, we performed immunologic analysis in the lungs and sera. RESULTS: The rs5743899 GG genotype was associated with rapid deterioration in FVC over time, which demonstrated significant annual decline in the retrospective cohort (vs AA, P = .0006; vs AG, P < .0001), prospective cohort (vs AA, P < .0001; vs AG, P = .003), and combined cohort (both P < .0001). The patients with the GG genotype demonstrated lower transcription-translation levels of TOLLIP as well as increased phosphorylation of Smad2 and inhibitor of kappa B in the lung tissues and exhibited higher serum levels of periostin, IL-1α, IL-1ß, IL-6, IL-8, tumor necrosis factor α, and IFN-γ. INTERPRETATION: The functional changes by TOLLIP variant were associated with rapid FVC decline through dysregulated Smad/transforming growth factor ß and NF-κB signaling in CHP.

Novel acute hypersensitivity pneumonitis model induced by airway mycosis and high dose lipopolysaccharide.

BACKGROUND: Inhalation of fungal spores is a strong risk factor for severe asthma and experimentally leads to development of airway mycosis and asthma-like disease in mice. However, in addition to fungal spores, humans are simultaneously exposed to other inflammatory agents such as lipopolysaccharide (LPS), with uncertain relevance to disease expression. To determine how high dose inhalation of LPS influences the expression of allergic airway disease induced by the allergenic mold Aspergillus niger (A. niger). METHODS: C57BL/6J mice were intranasally challenged with the viable spores of A. niger with and without 1 µg of LPS over two weeks. Changes in airway hyperreactivity, airway and lung inflammatory cell recruitment, antigen-specific immunoglobulins, and histopathology were determined. RESULTS: In comparison to mice challenged only with A. niger, addition of LPS (1 µg) to A. niger abrogated airway hyperresponsiveness and strongly attenuated airway eosinophilia, PAS+ goblet cells and TH2 responses while enhancing TH1 and TH17 cell recruitment to lung. Addition of LPS resulted in more severe, diffuse lung inflammation with scattered, loosely-formed parenchymal granulomas, but failed to alter fungus-induced IgE and IgG antibodies. CONCLUSIONS: In contrast to the strongly allergic lung phenotype induced by fungal spores alone, addition of a relatively high dose of LPS abrogates asthma-like features, replacing them with a phenotype more consistent with acute hypersensitivity pneumonitis (HP). These findings extend the already established link between airway mycosis and asthma to HP and describe a robust model for further dissecting the pathophysiology of HP.

[Hypersensitivity Pneumonitis - an important differential diagnosis of infiltrative lung diseases]. / Exogen allergische Alveolitis ­ Eine wichtige Differenzialdiagnose der infiltrativen Lungenerkrankungen.

Hypersensitivity pneumonitis (HP) is an inflammatory and/or fibrotic disease of the lung parenchyma and terminal bronchioles caused by an allergic reaction to inhaled antigens. The immune response following antigen exposure results in lymphocytic inflammation as well as granuloma formation.The typical histologic pattern of HP consists of cellular interstitial pneumonia, cellular bronchiolitis, and epithelioid cell granulomas. The additional presence of fibrosis has a significant impact on the course as well as the prognosis of the disease and represents a therapeutic approach. Therefore, a classification into a non-fibrotic and a fibrotic phenotype is proposed.The diagnosis of HP is made by high-resolution computed tomography (HRCT) of the lung, evaluation of possible antigen exposure, and bronchoscopy with bronchoalveolar lavage and, if necessary, forceps biopsy. If the diagnosis is inconclusive, transbronchial cryobiopsy or surgical lung biopsy may need to follow. A multidisciplinary board is critical in making the diagnosis.

Prognostic role of NK cell percentages in bronchoalveolar lavage from patients with different fibrotic interstitial lung diseases.

BAL cellularity and lymphocyte immunophenotyping offer insights into lung inflammatory status. Natural killer (NK) cells are efficient effector cells, producing pro-inflammatory cytokines. A better understanding of the biology of NK cells in BAL in the lungs is necessary to improve the pathogenesis of fibrotic ILD and develop prospective targeted treatments. Our aim was to analyse NK and NKT-like cell percentages in BAL from 159 patients with different ILD: f-HP, f-NSIP, IPF and CTD-ILD, to evaluate their potential diagnostic/prognostic role. BAL NK cell percentages showed significantly higher values in IPF than in f-HP and f-NSIP, while BAL NKT-like cells showed significantly lower values in the f-NSIP than the f-HP and IPF. A cut-off of 4%NK cells in BAL of IPF showed a significant difference in survival rate. It suggests a possible new marker of survival and raises the possibility of new targeted approach in treatment and management of IPF.

Barriers to antigen detection and avoidance in chronic hypersensitivity pneumonitis in the United States.

BACKGROUND: Chronic hypersensitivity pneumonitis (CHP) is an interstitial lung disease (ILD) caused by long term exposure to an offending antigen. Antigen avoidance is associated with improved outcomes. We are unable to identify the antigen source in approximately half of patients. When an antigen is successfully identified, patients have difficulty with avoidance. METHODS: We conducted three structured group discussions with US based ILD specialists utilizing the nominal group technique (NGT). Participants listed barriers to antigen detection and avoidance in CHP. Each participant ranked what they perceived to be the top three barriers in the list in terms of importance. The master list of barriers was consolidated across the three groups into themes that were prioritized based on receiving the highest rankings by participants. RESULTS: Twenty-five physicians participated; 56% had experience caring for CHP patients for ≥ 16 years. Sixty barriers to antigen detection were categorized into seven themes of which the top three were: 1. unclear significance of identified exposures; 2. gaps in clinical knowledge and testing capabilities; 3. there are many unknown and undiscovered antigens. Twenty-eight barriers to antigen avoidance were categorized into five themes of which the top three were: 1. patient limitations, financial barriers and lack of resources; 2. individual patient beliefs, emotions and attachments to the antigen source; and 3. gaps in clinical knowledge and testing capabilities. CONCLUSIONS: This study uncovered challenges at the individual patient, organizational, and societal levels and ranked them in terms of level of importance. These findings provide information to guide development and validation of multidisciplinary support and interventions geared towards antigen identification and avoidance in CHP.

Serum levels of IgG antibodies against Aspergillus fumigatus and the risk of hypersensitivity pneumonitis and other interstitial lung diseases.

Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) caused by the inhalation of antigens. Antigen-specific IgG antibodies (sIgG) are used as biomarkers of exposure when diagnosing HP, but little is known about the longitudinal relation between antibody levels and risk of HP or other ILD. In a follow-up design, we explored the relationship between sIgG antibodies against Aspergillus fumigatus and the diagnosis of HP in 647 subjects suspected of HP. We showed that IgG levels above the reference value resulted in a hazard ratio of 9.5 for subsequent HP. Our findings support a relationship between high levels of sIgG against A. fumigatus and risk of HP.

Executive summary diagnosis and evaluation of hypersensitivity pneumonitis: CHEST guideline and expert panel report [Pré-print]

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. 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. 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. 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.

Diagnosis and evaluation of hypersensitivity pneumonitis: CHEST guideline and expert panel report [Pré-print]

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. 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. 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. 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.

Performance of a diagnostic algorithm for fibrotic hypersensitivity pneumonitis. A case-control study.

BACKGROUND: The differential diagnosis fibrotic hypersensitivity pneumonitis (HP) versus idiopathic pulmonary fibrosis (IPF) is important but challenging. Recent diagnostic guidelines for HP emphasize including multidisciplinary discussion (MDD) in the diagnostic process, however MDD is not comprehensively available. We aimed to establish the diagnostic accuracy and prognostic validity of a previously proposed HP diagnostic algorithm that foregoes MDD. METHODS: We tested the algorithm in patients with an MDD diagnosis of fibrotic HP or IPF (case control study) and determined diagnostic test performances for diagnostic confidences of ≥ 90% and ≥ 70%. Prognostic validity was established using Cox proportional hazards models. RESULTS: Thirty-one patients with fibrotic HP and 50 IPF patients were included. The algorithm-derived ≥ 90% confidence level for HP had high specificity (0.94, 95% confidence interval [CI] 0.83-0.99), but low sensitivity (0.35 [95%CI 0.19-0.55], J-index 0.29). Test performance was improved for the ≥ 70% confidence level (J-index 0.64) with a specificity of 0.90 (95%CI 0.78-0.97), and a sensitivity of 0.74 (95%CI 0.55-0.88). MDD fibrotic HP diagnosis was strongly associated with lower risk of death (adjusted hazard ratio [HR] 0.10 [0.01-0.92], p = 0.04), whereas the algorithm-derived ≥ 70% and ≥ 90% confidence diagnoses were not significantly associated with survival (adjusted HR 0.37 [0.07-1.80], p = 0.22, and adjusted HR 0.41 [0.05-3.25], p = 0.39, respectively). CONCLUSION: The algorithm-derived ≥ 70% diagnostic confidence had satisfactory test performance for MDD-HP diagnosis, with insufficient sensitivity for ≥ 90% confidence. The lowest risk of death in the MDD-derived HP diagnosis validates the reference standard and suggests that a diagnostic algorithm not including MDD, might not replace the latter.

IL-17A-Secreting Memory γδ T Cells Play a Pivotal Role in Sensitization and Development of Hypersensitivity Pneumonitis.

Hypersensitivity pneumonitis (HP) typically presents with interstitial inflammation and granulomas induced by an aberrant immune response to inhaled Ags in sensitized individuals. Although IL-17A is involved in the development of HP, the cellular sources of IL-17A and the mechanisms by which IL-17A contributes to granuloma formation remain unclear. Recent studies report that γδ T cells produce IL-17A and exhibit memory properties in various diseases. Therefore, we focused on IL-17A-secreting memory γδ T cells in the sensitization phase and aimed to elucidate the mechanisms by which IL-17A contributes to granuloma formation in HP. We induced a mouse model of HP using pigeon dropping extract (PDE) in wild-type and IL-17A knockout (IL-17A-/-) mice. IL-17A-/- mice exhibited reduced granulomatous areas, attenuated aggregation of CD11b+ alveolar macrophages, and reduced levels of CCL2, CCL4, and CCL5 in the bronchoalveolar lavage fluid. Among IL-17A+ cells, more γδ T cells than CD4+ cells were detected after intranasal PDE administration. Interestingly, the expansion of IL-17A-secreting Vγ4+ or Vγ1-Vγ4- cells of convalescent mice was enhanced in response to the sensitizing Ag. Additionally, coculture of macrophages with PDE and Vγ4+ cells purified from PDE-exposed convalescent mice produced significantly more IL-17A than coculture with Vγ4+ cells from naive mice. Our findings demonstrate that in the sensitization phase of HP, IL-17A-secreting memory γδ T cells play a pivotal role. Furthermore, we characterized the IL-17A/CCL2, CCL4, CCL5/CD11b+ alveolar macrophage axis, which underlies granuloma formation in HP. These findings may lead to new clinical examinations or therapeutic targets for HP.

Hypersensitivity pneumonitis: clinical, radiological and pathological profile of 103 patients from North India.

Hypersensitivity pneumonitis (HP) is an interstitial lung disease, commonly occurring due to exposure to various inciting agent related to occupation. Few studies have shown that it can also occur without any occupation exposure. In this study we are presenting clinical, radiological and bronchoscopic finding of 103 HP patients. We retrospective analysis of 5½ years HP patient's data from a chest institute of India. The diagnosis of HP was considered with following criteria: i) known exposure to an inciting antigen; ii) presence of respiratory symptoms; iii) radiologic evidence of diffuse lung disease; iv) no other identifiable cause; v) lung biopsy specimen that demonstrated features of HP; and vi) bronchoalveolar lavage lymphocytosis (≥30%). The mean ±SD age was 47±12.8 years; 67% were female. The common symptoms were cough (97%) and dyspnea (91%). History of exposure to inciting agent was present in 61% with pigeon exposure being the most common (56%). Majority of patients (86%) were having chronic symptoms for >6 months. On 6MWT oxygen desaturation >4% was seen in 57% patients. Centrilobular nodules (61%) and ground glass opacity (47.5%) were common finding on HRCT chest. Bronchoalveolar lavage (BAL) lymphocytosis >30% was present in 48.5% and histopathological diagnosis HP on transbronchial lung biopsy (TBLB) and/or endobronchial lung biopsy (EBLB) was in 50% patients. HP is exposure related environmental disease, as it can occur without any occupational history. Bronchoscopy with BAL and lung biopsy should do in all suspected cases to confirm diagnosis in our country as it is less invasive, day care procedure with less complication.

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

Background: This guideline addresses the diagnosis of hypersensitivity pneumonitis (HP). It represents a collaborative effort among the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax.Methods: Systematic reviews were performed for six questions. The evidence was discussed, and then recommendations were formulated by a multidisciplinary committee of experts in the field of interstitial lung disease and HP using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.Results: The guideline committee defined HP, and clinical, radiographic, and pathological features were described. HP was classified into nonfibrotic and fibrotic phenotypes. There was limited evidence that was directly applicable to all questions. The need for a thorough history and a validated questionnaire to identify potential exposures was agreed on. Serum IgG testing against potential antigens associated with HP was suggested to identify potential exposures. For patients with nonfibrotic HP, a recommendation was made in favor of obtaining bronchoalveolar lavage (BAL) fluid for lymphocyte cellular analysis, and suggestions for transbronchial lung biopsy and surgical lung biopsy were also made. For patients with fibrotic HP, suggestions were made in favor of obtaining BAL for lymphocyte cellular analysis, transbronchial lung cryobiopsy, and surgical lung biopsy. Diagnostic criteria were established, and a diagnostic algorithm was created by expert consensus. Knowledge gaps were identified as future research directions.Conclusions: The guideline committee developed a systematic approach to the diagnosis of HP. The approach should be reevaluated as new evidence accumulates.

Chronic Hypersensitivity Pneumonitis, an Interstitial Lung Disease with Distinct Molecular Signatures.

Rationale: Chronic hypersensitivity pneumonitis (CHP) is caused by an immune response to antigen inhalation and is characterized by variable histopathological and clinical features. A subset of subjects with CHP have usual interstitial pneumonia and appear to be clinically similar to subjects with idiopathic pulmonary fibrosis (IPF).Objectives: To determine the common and unique molecular features of CHP and IPF.Methods: Transcriptome analysis of lung samples from CHP (n = 82), IPF (n = 103), and unaffected controls (n = 103) was conducted. Differential gene expression was determined adjusting for sex, race, age, and smoking history and using false discovery rate to control for multiple comparisons.Measurements and Main Results: When compared with controls, we identified 413 upregulated and 317 downregulated genes in CHP and 861 upregulated and 322 downregulated genes in IPF. Concordantly upregulated or downregulated genes in CHP and IPF were related to collagen catabolic processes and epithelial development, whereas genes specific to CHP (differentially expressed in CHP when compared with control and not differentially expressed in IPF) were related to chemokine-mediated signaling and immune responsiveness. Using weighted gene coexpression network analysis, we found that among subjects with CHP, genes involved in adaptive immunity or epithelial cell development were associated with improved or reduced lung function, respectively, and that MUC5B expression was associated with epithelial cell development. MUC5B expression was also associated with lung fibrosis and honeycombing.Conclusions: Gene expression analysis of CHP and IPF identified signatures common to CHP and IPF, as well as genes uniquely expressed in CHP. Select modules of gene expression are characterized by distinct clinical and pathological features of CHP.

Age-associated B Cells Appear in Patients with Granulomatous Lung Diseases.

Rationale: A subpopulation of B cells (age-associated B cells [ABCs]) is increased in mice and humans with infections or autoimmune diseases. Because depletion of these cells might be valuable in patients with certain lung diseases, the goal was to find out if ABC-like cells were at elevated levels in such patients.Objectives: To measure ABC-like cell percentages in patients with lung granulomatous diseases.Methods: Peripheral blood and BAL cells from patients with sarcoidosis, beryllium sensitivity, or hypersensitivity pneumonitis and healthy subjects were analyzed for the percentage of B cells that were ABC-like, defined by expression of CD11c, low levels of CD21, FcRL 1-5 (Fc receptor-like protein 1-5) expression, and, in some cases, T-bet.Measurements and Main Results: ABC-like cells in blood were at low percentages in healthy subjects and higher percentages in patients with sarcoidosis as well as at high percentages among BAL cells of patients with sarcoidosis, beryllium disease, and hypersensitivity pneumonitis. Treatment of patients with sarcoidosis led to reduced percentages of ABC-like cells in blood.Conclusions: Increased levels of ABC-like cells in patients with sarcoidosis may be useful in diagnosis. The increase in percentage of ABC-like cells in patients with lung granulomatous diseases and decrease in treated patients suggests that depletion of these cells may be valuable.

Prognostic factors in chronic hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP) is an immunologically mediated lung disease resulting from exposure to inhaled environmental antigens. Prognosis is variable, with a subset of patients developing progressive fibrosis leading to respiratory failure and death. Therefore, there is an urgent need to identify factors which predict prognosis and survival in patients with HP. We undertook a narrative review of existing evidence to identify prognostic factors in patients with chronic HP. Patient demographics, smoking history, extent of antigen exposure and comorbidities all have reported associations with disease outcome, and physiological, radiological and laboratory markers have been shown to predict overall survival. While no single marker has been demonstrated to accurately and reliably predict prognosis, older age, more severe impairment of pulmonary function at baseline and established fibrosis on either biopsy or high-resolution computed tomography are consistently associated with worse survival. The vast majority of existing studies are retrospective, and this review identifies a need for prospective longitudinal studies with serial assessment of respiratory health to ascertain factors associated with nonfatal deterioration. Future developments, including the development of HP-specific composite scores may help further improve our ability to predict outcomes for individual patients.

S1P1 Contributes to Endotoxin-enhanced B-Cell Functions Involved in Hypersensitivity Pneumonitis.

In a proportion of patients with hypersensitivity pneumonitis, the biological and environmental factors that sustain inflammation are ill defined, resulting in no effective treatment option. Bioaerosols found in occupational settings are complex and often include Toll-like receptor ligands, such as endotoxins. How Toll-like receptor ligands contribute to the persistence of hypersensitivity pneumonitis, however, remains poorly understood. In a previous study, we found that an S1P1 (sphingosine-1-phosphate receptor 1) agonist prevented the reactivation of antigen-driven B-cell responses in the lung. Here, we assessed the impact of endotoxins on B-cell activation in preexisting hypersensitivity pneumonitis and the role of S1P1 in this phenomenon. The impact of endotoxins on pre-established hypersensitivity pneumonitis was studied in vivo. S1P1 levels were tracked on B cells in the course of the disease using S1P1-eGFP knockin mice, and the role of S1P1 on B-cell functions was assessed using pharmacological tools. S1P1 was found on B cells in experimental hypersensitivity pneumonitis. Endotoxin exposure enhanced neutrophil accumulation in the BAL of mice with experimental hypersensitivity pneumonitis. This was associated with enhanced CD69 cell-surface expression on lymphocytes in the BAL. In isolated B cells, endotoxins increased cell-surface levels of costimulatory molecules and CD69, which was prevented by an S1P1 agonist. S1P1 modulators also reduced TNF production by B cells and their capacity to trigger T-cell cooperation ex vivo. An S1P1 ligand directly inhibited endotoxin-induced B-cell activation.

Histology is critical but not always for the diagnosis of chronic hypersensitivity pneumonitis.

BACKGROUND: The diagnosis of chronic hypersensitivity pneumonitis (CHP) is often based on the pathology, but evidence is scarce that a pathological diagnosis of CHP may mislead the multidisciplinary diagnosis. METHOD: We enrolled patients from the consultation case archive whose pathological findings were suggestive of CHP but had a multidisciplinary diagnosis of non-CHP. The histopathological slides were sent to another pathologist, and the ones confirmed with CHP were sent for an additional multidisciplinary discussion (MDD). We examined clinicopathological features of the cases confirmed to be non-CHP through MDD. RESULTS: Among the 243 cases, five were diagnosed as non-CHP through an additional MDD. The most common causes of discrepancy were the presence of strong autoimmune features, a low lymphocyte level in the bronchoalveolar lavage fluid, and a lack of nodular shadow or mosaic attenuation on computed tomography. CONCLUSIONS: Cases of suspected CHP on pathology may be determined to be non-CHP through MDD.

Pantoea agglomerans chronic exposure induces epithelial-mesenchymal transition in human lung epithelial cells and mice lungs.

Pantoea agglomerans is gram-negative bacteria widely distributed in nature. It predominates in inhalable dust from grain, herbs, and flax, and was identified as the most important cause of hypersensitivity pneumonitis (HP) in eastern Poland. To better understand the molecular mechanism of HP development studies focused on the interactions between P. agglomerans and alveolar epithelial cells as well as lung tissue with particular emphasis on the epithelial-mesenchymal transition (EMT). The studies were conducted on human normal lung epithelial NL20 cells and mice strain C57BL/6J. Cells and mice underwent chronic exposure to saline extract of P. agglomerans (SE-PA). Morphological changes were evaluated under light microscopy, the concentration of fibrosis markers was examined by the ELISA method, while the expression of genes involved in EMT was evaluated by RealTime PCR. During incubation with SE-PA epithelial cells underwent conversion and assumed fibroblast phenotype characterized by a decrease in epithelial cells markers (CDH1, CLDN1, JUP) and increase in mesenchymal cells markers (FN1, VIM, CDH2). Mice lungs collected after 14 days of SE-PA treatment revealed inflammation with marked lymphocytes infiltration. The intensified inflammatory process accompanied by increased proliferation of fibrous connective tissue was noted in mice lungs after 28 days of SE-PA exposure. Histological changes correlated with an increase of fibrosis markers (hydroxyproline, collagens), downregulation of epithelial markers (Cdh1, Cldn1, Jup, Ocln) and upregulation of myofibroblasts markers (Acta2, Cdh2, Fn1, Vim). Obtained results revealed SE-PA ability to induce EMT in human lung epithelial cells and mice lung tissue, with the scale of changes proportional to the time of treatment.