PLA2R-positive membranous nephropathy in IgG4-related disease.

BACKGROUND: IgG4-related disease (IgG4-RD) is a fibroinflammatory disease that affects multiple organs, including the pancreas, lacrimal glands, salivary glands, periaortic/retroperitoneum, and kidney. Interstitial nephritis is a typical renal disorder associated with IgG4-RD, but membranous nephropathy is also seen in some cases. CASE PRESENTATION: Herein we report on the case of a 77-year-old male patient with nephrotic syndrome and IgG4-related lung disease. His serum phospholipase A2 receptor (PLA2R) antibody was positive. His renal biopsy specimen was also positive for PLA2R. The renal biopsy specimen showed membranous nephropathy with equal IgG3 and IgG4 immunofluorescence staining and no interstitial nephritis, suggesting IgG4-RD manifesting as membranous nephropathy. CONCLUSIONS: Nephrotic syndrome caused by membranous nephropathy is sometimes associated with IgG4-RD. In such cases, even if serum PLA2R antibody is positive, it should be considered that the membranous nephropathy may be secondary to IgG4-RD.

Clinical characteristics of allergic bronchopulmonary mycosis caused by Schizophyllum commune.

BACKGROUND: Allergic bronchopulmonary mycosis (ABPM) is an allergic disease caused by type I and type III hypersensitivity to environmental fungi. Schizophyllum commune, a basidiomycete fungus, is one of the most common fungi that causes non-Aspergillus ABPM. OBJECTIVE: Herein, we attempted to clarify the clinical characteristics of ABPM caused by S. commune (ABPM-Sc) compared with those of allergic bronchopulmonary aspergillosis (ABPA). METHODS: Patients with ABPM-Sc or ABPA were recruited from a nationwide survey in Japan, a multicenter cohort, and a fungal database at the Medical Mycology Research Center of Chiba University. The definition of culture-positive ABPM-Sc/ABPA is as follows: (1) fulfills five or more of the 10 diagnostic criteria for ABPM proposed by Asano et al., and (2) positive culture of S. commune/Aspergillus spp. in sputum, bronchial lavage fluid, or mucus plugs in the bronchi. RESULTS: Thirty patients with ABPM-Sc and 46 with ABPA were recruited. Patients with ABPM-Sc exhibited less severe asthma and presented with better pulmonary function than those with ABPA (p = 0.008-0.03). Central bronchiectasis was more common in ABPM-Sc than that in ABPA, whereas peripheral lung lesions, including infiltrates/ground-glass opacities or fibrotic/cystic changes, were less frequent in ABPM-Sc. Aspergillus fumigatus-specific immunoglobulin (Ig)E was negative in 10 patients (34%) with ABPM-Sc, who demonstrated a lower prevalence of asthma and levels of total serum IgE than those with ABPM-Sc positive for A. fumigatus-specific IgE or ABPA. CONCLUSIONS: Clinical characteristics of ABPM-Sc, especially those negative for A. fumigatus-specific IgE, differed from those of ABPA.

Concordance between transbronchial lung cryobiopsy and surgical lung biopsy for interstitial lung disease in the same patients.

BACKGROUND: The diagnostic accuracy and safety of transbronchial lung cryobiopsy (TBLC) via a flexible bronchoscope under sedation compared with that of surgical lung biopsy (SLB) in the same patients is unknown. METHODS: Retrospectively the data of fifty-two patients with interstitial lung diseases (median age: 63.5 years; 21 auto-antibody positive) who underwent TBLC followed by SLB (median time from TBLC to SLB: 57 days) was collected. The samples from TBLC and SLB were randomly labelled to mask the relationship between the two samples. Diagnosis was made independently by pathologists, radiologists, and pulmonary physicians in a stepwise manner, and a final diagnosis was made at multidisciplinary discussion (MDD). In each diagnostic step the specific diagnosis, the diagnostic confidence level, idiopathic pulmonary fibrosis (IPF) diagnostic guideline criteria, and treatment strategy were recorded. RESULTS: Without clinical and radiological information, the agreement between the histological diagnoses by TBLC and SLB was 42.3% (kappa [κ] = 0.23, 95% confidence interval [CI]: 0.08-0.39). However, the agreement between the TBLC-MDD and SLB-MDD diagnoses and IPF/non-IPF diagnosis using the two biopsy methods was 65.4% (κ = 0.57, 95% CI: 0.42-0.73) and 90.4% (47/52), respectively. Out of 38 (73.1%) cases diagnosed with high or definite confidence at TBLC-MDD, 29 had concordant SLB-MDD diagnoses (agreement: 76.3%, κ = 0.71, 95% CI: 0.55-0.87), and the agreement for IPF/non-IPF diagnoses was 97.4% (37/38). By adding the pathological diagnosis, the inter-observer agreement of clinical diagnosis improved from κ = 0.22 to κ = 0.42 for TBLC and from κ = 0.27 to κ = 0.38 for SLB, and the prevalence of high or definite diagnostic confidence improved from 23.0% to 73.0% and from 17.3% to 73.0%, respectively. Of all 383 TBLC performed during the same period, pneumothorax occurred in 5.0% of cases, and no severe bleeding, acute exacerbation of interstitial lung disease, or fatal event was observed. CONCLUSIONS: TBLC via a flexible bronchoscope under deep sedation is safely performed, and the TBLC-MDD diagnosis with a high or definite confidence level is concordant with the SLB-MDD diagnosis in the same patients.

Nationwide retrospective observational study of idiopathic dendriform pulmonary ossification: clinical features with a progressive phenotype.

BACKGROUND: Diffuse pulmonary ossification is a specific lung condition that is accompanied by underlying diseases. However, idiopathic dendriform pulmonary ossification (IDPO) is extremely rare, and the clinical features remain unclear. In this study, we aimed to report the clinical characteristics of IDPO. METHODS: We conducted a nationwide survey of patients with IDPO from 2017 to 2019 in Japan and evaluated the clinical, radiological, and histopathological findings of patients diagnosed with IDPO. RESULTS: Twenty-two cases of IDPO were identified. Most subjects (82%) were male, aged 22-56 years (mean (SD), 37.9 (9.1)) at diagnosis. Nearly 80% of the subjects were asymptomatic, and the condition was discovered during a medical check-up. However, 36% of the subjects showed a decline in forced vital capacity (%FVC) predicted <80% at diagnosis. The typical radiological features of high-resolution CT (HRCT) are calcified branching structures that are predominantly distributed in the lower lung fields without any other conspicuous finding. Histopathological analysis also showed dendriform ossified lesions from the intraluminal areas to interstitial areas. Notably, during the follow-up period of 20 years, disease progression was found in 88% on HRCT and more than 50% on pulmonary function tests (FVC and/or forced expiratory volume in 1 s). Two cases with rapid decline of 10% /year in %FVC predicted were observed.)) at diagnosis. Nearly 80% of the subjects were asymptomatic, and the condition was discovered during a medical check-up. However, 36% of the subjects showed a decline in forced vital capacity (%FVC) predicted <80% at diagnosis. The typical radiological features of high-resolution CT (HRCT) are calcified branching structures that are predominantly distributed in the lower lung fields without any other conspicuous finding. Histopathological analysis also showed dendriform ossified lesions from the intraluminal areas to interstitial areas. Notably, during the follow-up period of 20 years, disease progression was found in 88% on HRCT and more than 50% on pulmonary function tests (FVC and/or forced expiratory volume in 1 s). Two cases with rapid decline of 10% /year in %FVC predicted were observed. CONCLUSIONS: IDPO develops at a young age with gradually progressive phenotype. Further research and long-term (>20 years) follow-up are required to clarify the pathogenesis and clinical findings in IDPO.

Zoonotic infection caused by Onchocerca japonica (Nematoda: Filarioidea) in a 69-year-old woman in Kanto Region, Eastern Honshu, Japan.

Reports of zoonotic infections caused by the filarial nematode Onchocerca japonica have recently increased in Japan. A 69-year-old woman living in Sosa City, Chiba Prefecture, Kanto Region, Honshu, developed a painful nodule at the metacarpophalangeal joint of the index finger of her right hand. The causative agent was identified as a female O. japonica based on the histopathological characteristics (i.e., cuticle with transverse triangular ridges but without inner striae) of the biopsy specimens of the nodule. The species identification was corroborated by cox1 gene sequencing of the worm tissues isolated from paraffin-embedded sections of the specimens. Subsequent to the excision of the nodule, followed by anthelmintic treatment, the patient remained asymptomatic. Human infection with O. japonica has not previously been reported in Kanto Region, Eastern Honshu. The present case is likely linked to the recent expansion of the geographic range of the Japanese wild boar into this area.

Usual Interstitial Pneumonia Pattern Interstitial Lung Disease Developed in a Patient with IgG4-related Chronic Sclerosing Sialadenitis.

A 69-year-old man was diagnosed with immunoglobulin (Ig) G4-related disease (IgG4-RD) at 62 years old. At that time, he had high serum IgG4 levels and bilateral submandibular gland swelling on CT; thus, a gland biopsy was performed. Because a reticular shadow was found on chest CT, a lung surgical biopsy was also performed. The specimens revealed usual interstitial pneumonia (UIP) pattern interstitial pneumonia with some IgG4-positive cells. The patient was subsequently followed up without treatment. His forced vital capacity and radiological findings progressively deteriorated, consistent with UIP pattern interstitial lung disease but different from a lung lesion of IgG4-RD.

Post-coronavirus disease 2019 organizing pneumonia confirmed pathologically by video-assisted thoracoscopic surgery.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, has become a global pandemic. Many survivors of serious COVID-19 pneumonia have long-term residual pulmonary disease. However, there is little documentation of the histopathological characteristics of lung sequelae post-COVID-19 and effective treatments. We present two Japanese cases of lung sequelae post-COVID-19. The patients were histopathologically diagnosed with organizing pneumonia (OP) or OP with fibrosis and no diffuse alveolar damage on video-assisted thoracoscopic surgery. Case 1, who had been diagnosed with OP, was successfully treated with corticosteroid and other immunosuppressive agents over a 6-month period. Although case 2, who had been diagnosed with OP with fibrosis, had a partial and unsatisfactory response to immunosuppressive agents, the patient responded to antifibrotic treatment including nintedanib.

Eosinophilic bronchiolitis successfully treated with benralizumab.

A 53-year-old non-smoking Japanese woman was admitted to our hospital with a 20-year history of wet cough and dyspnoea on exertion. Bronchial asthma (BA) had been diagnosed 20 years earlier. Although she has been treated with high-dose inhaled corticosteroid, she had experienced frequent exacerbation of BA, and short-term oral corticosteroid bursts were occasionally administered. High-resolution CT of the chest revealed diffuse centrilobular nodules with bronchial wall thickening and patchy ground-glass opacities in both lungs. Lung biopsy specimens showed widespread cellular bronchiolitis with follicle formations in the membranous and respiratory bronchioles, accompanied by marked infiltration of plasma cells and eosinophils. In addition, immunohistochemical immunoglobulin G4 (IgG4) staining revealed many IgG4-positive plasma cells, and the ratio of IgG4-positive cells to IgG-positive cells exceeded 40%. The final diagnosis was eosinophilic bronchiolitis with marked IgG4-positive plasma cell infiltration in association with BA. With benralizumab therapy, her clinical condition dramatically improved.

Intractable diffuse pulmonary diseases: Manual for diagnosis and treatment.

This manual has been compiled by a joint production committee with the Diffuse Lung Disease Assembly of the Japanese Respiratory Society (JRS) to provide a practical manual for the epidemiology, diagnosis, and treatment of intractable diffuse pulmonary diseases. The contents are based upon the results of research into these diseases by the Diffuse Pulmonary Diseases Study Group (principal researcher: Sakae Homma) supported by the FY2014-FY2016 Health and Labor Sciences Research Grant on Intractable Diseases. This manual focuses on: 1) pulmonary alveolar microlithiasis, 2) bronchiolitis obliterans, and 3) Hermansky-Pudlak Syndrome with interstitial pneumonia. As these are rare/intractable diffuse lung diseases (2 and 3 were first recognized as specified intractable diseases in 2015), there have not been sufficient epidemiological studies made, and there has been little progress in formulating diagnostic criteria and severity scales; however, the results of Japan's first surveys and research into such details are presented herein. In addition, the manual provides treatment guidance and actual cases for each disease, aiming to assist in the establishment of future modalities. The manual was produced with the goal of enabling clinicians specialized in respiratory apparatus to handle these diseases in clinical settings and of further advancing future research and treatment.

Acute exacerbation in chronic bird fancier's lung with pleuroparenchymal fibroelastosis.

A 71-year-old non-smoker woman was admitted to our hospital complaining of a six-month history of dry cough. She had kept java sparrow for nine years and has been raising budgerigars for the previous eight months. High-resolution computed tomography (HRCT) images of the chest revealed reticulonodular lesions predominantly in the bilateral upper lobes. Surgical lung biopsy specimens showed non-caseous epithelioid cell granulomas in the alveolar spaces, including irregular and centrilobular fibrosis with pleuroparenchymal fibroelastosis. When she started using a duck feather duvet at home, she developed dyspnoea and chest HRCT abnormalities progressively deteriorated. The results of precipitation of antibodies against duck feather, java sparrow, and budgerigars dropping extracts were positive in sera. Consequently, the patient was diagnosed as having chronic bird fancier's lung with acute exacerbation caused by the use of a feather duvet. After combination treatments with corticosteroid and cyclosporine, her respiratory symptoms and reticulonodular shadow immediately improved.

FOXL1 Regulates Lung Fibroblast Function via Multiple Mechanisms.

Fibroblasts provide a structural framework for multiple organs and are essential for wound repair and fibrotic processes. Here, we demonstrate functional roles of FOXL1 (forkhead box L1), a transcription factor that characterizes the pulmonary origin of lung fibroblasts. We detected high FOXL1 transcripts associated with DNA hypomethylation and super-enhancer formation in lung fibroblasts, which is in contrast with fibroblasts derived from other organs. RNA in situ hybridization and immunohistochemistry in normal lung tissue indicated that FOXL1 mRNA and protein are expressed in submucosal interstitial cells together with airway epithelial cells. Transcriptome analysis revealed that FOXL1 could control a broad array of genes that potentiate fibroblast function, including TAZ (transcriptional coactivator with PDZ-binding motif)/YAP (Yes-associated protein) signature genes and PDGFRα (platelet-derived growth factor receptor-α). FOXL1 silencing in lung fibroblasts attenuated cell growth and collagen gel contraction capacity, underscoring the functional importance of FOXL1 in fibroproliferative reactions. Of clinical importance, increased FOXL1 mRNA expression was found in fibroblasts of idiopathic pulmonary fibrosis lung tissue. Our observations suggest that FOXL1 regulates multiple functional aspects of lung fibroblasts as a key transcription factor and is involved in idiopathic pulmonary fibrosis pathogenesis.

Recent trends in the incidence of latent tuberculosis infection in Japanese patients with lung cancer: A small retrospective study.

Active tuberculosis is an important complication in Japanese lung cancer patients. We studied the generation-wise trend of latent tuberculosis infection (LTBI) among lung cancer patients. We analyzed background data including birth year, lung cancer status, and interferon-gamma release assay (IGRA) data of lung cancer patients who were admitted to National Hospital Organization Tokyo National Hospital from 2010 to 2016. Of the 1450 cases, 7 showed active tuberculosis and 45 had previous tuberculosis. Of the remaining 1398 patients, 795 underwent IGRAs and 120 (15%) of them were found to have LTBI. Patients with LTBI were older (p = 0.0005), and the proportion of smokers was also higher in this group (p = 0.0159) than among those without LTBI. LTBI incidence decreased from 33% among patients born in the 1920s to 21%, 15%, 9.8%, and 5.1% among those born in the 1930s, 1940s, 1950s, and after 1960, respectively. A significant decrease in the smoking adjusted risk ratio was also observed with every generation (p < 0.0001). Our study suggests that the total number of patients with active tuberculosis comorbid with lung cancer will greatly decrease in the future in Japan. However, owing to recent improvements in lung cancer prognosis due to advances in cancer medication, careful monitoring for active tuberculosis development may be required in lung cancer patients with LTBI.

Concordance between sequential transbronchial lung cryobiopsy and surgical lung biopsy in patients with diffuse interstitial lung disease.

BACKGROUND: Increasing evidence indicates the utility of transbronchial lung cryobiopsy (TBLC) for the diagnosis of interstitial lung disease (ILD). However, only one study has compared TBLC and surgical lung biopsy (SLB) performed on the same patients. METHODS: We identified seven patients with ILD with TBLC and SLB. We evaluated the clinical characteristics and made a pathological diagnosis based on the official ATS/ERS/JRS/ALAT clinical practice guideline of idiopathic pulmonary fibrosis with both TBLC and SLB. RESULTS: Six cases were diagnosed as Usual interstitial pneumonia (UIP) in both TBLC and SLB. One case was diagnosed as indeterminate for UIP with TBLC and probable UIP with SLB. Etiological diagnosis with TBLC and SLB were concordant in 2 cases of idiopathic pulmonary fibrosis (IPF) but discordant for other diagnoses. Major histological findings of UIP including dense fibrosis, peripheral distribution, and fibroblastic foci showed high concordance between TBLC and SLB, which implies that TBLC can reliably detect these features. In contrast, loose fibrosis, cellular infiltration, and airway disease showed poor concordance between the two methods. CONCLUSION: Our study showed that TBLC is useful for UIP diagnosis but not for other ILD. With a multidisciplinary approach, diagnosis of IPF may be determined by TBLC, whereas ILD other than IPF may require SLB.

Catalase expression of Propionibacterium acnes may contribute to intracellular persistence of the bacterium in sinus macrophages of lymph nodes affected by sarcoidosis.

Bacterial catalase is important for intracellular survival of the bacteria. This protein of Propionibacterium acnes, one of possible causes of sarcoidosis, induces hypersensitive Th1 immune responses in sarcoidosis patients. We examined catalase expression in cultured P. acnes isolated from 19 sarcoid and 18 control lymph nodes and immunohistochemical localization of the protein in lymph nodes from 43 sarcoidosis and 102 control patients using a novel P. acnes-specific antibody (PAC) that reacts with the catalase protein, together with the previously reported P. acnes-specific PAB and TIG antibodies. High catalase expression of P. acnes cells was found during stationary phase in more isolates from sarcoid than from non-sarcoid lymph nodes and was associated with bacterial survival under H2O2-induced oxidative stress. In many sarcoid and some control lymph nodes, catalase expression was detected at the outer margins of PAB-reactive Hamazaki-Wesenberg (HW) bodies in sinus macrophages, the same location as catalase expression on the surface of cultured P. acnes and the same distribution as bacterial cell membrane-bound lipoteichoic acid in HW bodies. Some or no catalase expression was detected in sarcoid granulomas with PAB reactivity or in clustered paracortical macrophages packed with many PAB-reactive small-round bodies. HW bodies expressing catalase may be persistent P. acnes in sinus macrophages whereas PAB-reactive small-round bodies with undetectable catalase may be activated P. acnes proliferating in paracortical macrophages. Intracellular proliferation of P. acnes in paracortical macrophages may lead to granuloma formation by this commensal bacterium in sarcoidosis patients with Th1 hypersensitivity to certain P. acnes antigens, including catalase.

Criteria for the diagnosis of idiopathic pleuroparenchymal fibroelastosis: A proposal.

BACKGROUND: Physicians have few opportunities to perform surgical lung biopsy (SLB) to diagnose idiopathic pleuroparenchymal fibroelastosis (IPPFE). Therefore, diagnostic criteria for IPPFE that do not require SLB must be established. Herein, we propose diagnostic criteria for IPPFE with and without SLB. METHODS AND RESULTS: The diagnostic criteria for IPPFE with SLB are histological, based on computed tomography (CT) lesions compatible with PPFE, predominantly in the upper lobes. The three diagnostic criteria for IPPFE without SLB are as follows: (1) radiologically possible IPPFE (a radiological criterion confirming CT lesions in both lung apexes, regardless of the lower lobe lesions); (2) radiologically probable IPPFE (also a radiological criterion, but mandatory to confirm chest radiograph findings of bilateral upward shift of the hilar structures and/or CT findings of volume loss of the upper lobes); (3) radiologically and physiologically probable IPPFE. Our data from 41 patients with IPPFE and 97 with idiopathic pulmonary fibrosis (IPF) showed that the percentage of the predicted values of the ratio of residual volume to total lung capacity (RV/TLC %pred.) ≥115% and body mass index (BMI) ≤20 kg/m2 plus RV/TLC %pred. ≥80% performed well for discriminating IPPFE from IPF. These parameters were thus added to criterion (3). CONCLUSIONS: We have proposed diagnostic criteria for IPPFE in patients with and without SLB. Both imaging criteria and physiological criteria using RV/TLC and BMI successfully discriminate IPPFE from chronic IIPs when SLB cannot be performed.

Ten Cases of Intestinal Tuberculosis Which Were Initially Misdiagnosed as Inflammatory Bowel Disease.

Objective Intestinal tuberculosis (ITB) and inflammatory bowel disease (IBD) frequently present with similar clinical, endoscopic and pathological features, therefore it is difficult to differentiate between them. The aim of this study was to elucidate the diagnostic delay and prognosis of ITB cases, initially misdiagnosed as IBD. Methods ITB cases were selected from the hospitalized patient list between April 2004 and March 2017 in a tuberculosis center in Japan. We retrospectively evaluated the initial diagnosis, clinical characteristics, endoscopic and pathological findings, bacterial examinations, treatment and prognosis. Results Among 66 ITB patients, ten patients were initially misdiagnosed as IBD. Seven patients were male and the median age was 60.5 years (23-74 years). After the diagnosis of IBD, all the patients were treated with mesalazine, in addition to corticosteroids in two patients and sequential azathioprine and infliximab in one. The median duration of diagnostic delay was 5.5 months (range 0.5-17 months). Eight patients had active pulmonary tuberculosis at the diagnosis of ITB. Acid-fast bacilli were confirmed in four of seven patients by reevaluation of the pathological specimens at the IBD diagnosis. Two patients needed intestinal resection and one with erroneous corticosteroid use for IBD died due to respiratory failure in spite of receiving appropriate treatment for tuberculosis. Conclusion ITB patients were frequently misdiagnosed and treated as IBD, thus resulting in a poor clinical outcome even after finally making a correct diagnosis and administering appropriate treatment. On diagnosis of IBD and/or treatment failure, chest radiograph and acid-fast bacilli of the pathological specimens should be carefully evaluated in order to rule out tuberculosis.

IL-9 Blockade Suppresses Silica-induced Lung Inflammation and Fibrosis in Mice.

Recapitulative animal models of idiopathic pulmonary fibrosis (IPF) and related diseases are lacking, which inhibits our ability to fully clarify the pathogenesis of these diseases. Although lung fibrosis in mouse models is often induced by bleomycin, silica-induced lung fibrosis is more sustainable and more progressive. Therefore, in this study, we sought to elucidate the mediator(s) responsible for the pathogenesis of lung fibrosis, through the use of a mouse model of silica-induced lung fibrosis. With a single nasal administration of 16 mg of silica, lung inflammation (assessed by elevated cellular components in the BAL fluids [BALFs]) and lung fibrosis (assessed by lung histology and lung hydroxyproline levels) were induced and sustained for as long as 24 weeks. Of the mediators measured in the BALFs, IL-9 was characteristically elevated gradually, and peaked at 24 weeks after silica administration. Treatment of silica-challenged mice with anti-IL-9-neutralizing antibody inhibited lung fibrosis, as assessed by lung hydroxyproline level, and suppressed the levels of major mediators, including IL-1ß, IL-6, IL-12, CCL2, CXCL1, and TNF-α in BALFs. Moreover, human lung specimens from patients with IPF have shown high expression of IL-9 in alveolar macrophages, CD4-positive cells, and receptors for IL-9 in airway epithelial cells. Collectively, these data suggest that IL-9 plays an important role in the pathogenesis of lung fibrosis in diseases such as IPF.

Allergic Bronchopulmonary Aspergillosis-A Luminal Hypereosinophilic Disease With Extracellular Trap Cell Death.

Allergic bronchopulmonary aspergillosis (ABPA) is characterized by an early allergic response and late-phase lung injury in response to repeated exposure to Aspergillus antigens, as a consequence of persistent fungal colonization of the airways. Here, we summarize the clinical and pathological features of ABPA, focusing on thick mucus plugging, a key observation in ABPA. Recent findings have indicated that luminal eosinophils undergo cytolytic extracellular trap cell death (ETosis) and release filamentous chromatin fibers (extracellular traps, ETs) by direct interaction with Aspergillus fumigatus. Production of ETs is considered to be an innate immune response against non-phagocytable pathogens using a "trap and kill" mechanism, although eosinophil ETs do not promote A. fumigatus damage or killing. Compared with neutrophils, eosinophil ETs are composed of stable and condensed chromatin fibers and thus might contribute to the higher viscosity of eosinophilic mucus. The major fate of massively accumulated eosinophils in the airways is ETosis, which potentially induces the release of toxic granule proteins and damage-associated molecular patterns, epithelial damage, and further decreases mucus clearance. This new perspective on ABPA as a luminal hypereosinophilic disease with ETosis/ETs could provide a better understanding of airway mucus plugging and contribute to future therapeutic strategies for this challenging disease.

Allergic bronchopulmonary mycosis - pathophysiology, histology, diagnosis, and treatment.

Allergic bronchopulmonary mycosis (ABPM) develops mainly in patients with asthma or cystic fibrosis via types I and III hypersensitivity reactions to filamentous fungi. Aspergillus spp., especially Aspergillus fumigatus, is the major causative fungus because of its small conidia, thermophilic hyphae, and ability to secrete serine proteases. The cardinal histological feature of ABPM is allergic (eosinophilic) mucin-harboring hyphae in the bronchi, for which the formation of extracellular DNA trap cell death (ETosis) of eosinophils induced by viable fungi is essential. Clinically, ABPM is characterized by peripheral blood eosinophilia, increased IgE levels in the serum, IgE and IgG antibodies specific for fungi, and characteristic radiographic findings; however, there are substantial differences in the clinical features of this disease between East and South Asian populations. Systemic corticosteroids and/or antifungal drugs effectively control acute diseases, but recurrences are quite common, and development of novel treatments are warranted to avoid adverse effects and emergence of drug-resistance due to prolonged treatment with corticosteroids and/or antifungal drugs.