Objective Community-acquired pneumonia (CAP) remains a major cause of death. No studies have reported the use of rapid influenza diagnostic tests (RIDT) for the etiological diagnosis, and the factors contributing to severity and mortality have not yet been fully investigated. The aim of this study was to review the etiologies of CAP using RIDT and to identify risk factors related to the severity and mortality of the disease. Methods This retrospective study assessed these factors in hospitalized patients, with special emphasis on microbial etiology. Results A total of 1,032 patients aged 63.9±18.3 years were studied, 66.2% of whom were men. Microbial identification was obtained in 57.0% of the cases. The most frequent causative microbial agents were Streptococcus pneumoniae, Mycoplasma pneumoniae and the influenza virus, and the second most frequent pathogens in the patients with severe CAP and the non-survivors were S. pneumoniae and the influenza virus. Age (≥65 years), chronic obstructive pulmonary disease, congestive heart failure, diabetes mellitus, dementia and Legionella spp. infection and polymicrobial infection were each found to be independent factors related to severity in the multivariate analysis, whereas "unidentified pathogen" was found to be an independent factor for non-severe CAP. Age (≥65 years), chronic pulmonary aspergillosis, post-lung cancer surgery and severe CAP were found to be independent factors for non-survival according to a multivariate analysis. Conclusion In addition to S. pneumoniae, the influenza virus was a frequent cause of CAP overall and a frequent causative pathogen in both severe cases of CAP and non-survivors. Legionella spp. infection and polymicrobial infection were found to be an independent factor for the severity of CAP along with advanced age and certain comorbidities. An advanced age, certain respiratory comorbidities and severe CAP were found to be important independent factors for the mortality of CAP.

Despite standard treatment with systemic corticosteroids and/or antifungal triazoles, a substantial proportion of patients with allergic bronchopulmonary aspergillosis (ABPA) experience frequent relapses and require long-term treatment despite unfavorable adverse effects. We investigated the efficacy and safety of anti-interleukin (IL)-5/IL-5 receptor α chain (Rα) monoclonal antibodies (mAbs) in patients with ABPA complicated by asthma. ABPA cases treated with anti-IL-5/IL-5Rα mAbs were collected from 132 medical institutes in 2018 and published case reports in Japan. Clinical outcomes, laboratory and physiological data, and radiographic findings during 32 weeks before and after treatment were retrospectively evaluated. We analyzed 29 cases of ABPA: 20 treated with mepolizumab and nine with benralizumab. Treatment with anti-IL-5/IL-5Rα mAbs reduced the frequency of exacerbations (p = 0.03), decreased the dose of oral corticosteroids (p < 0.01), and improved pulmonary function (p = 0.01). Mucus plugs in the bronchi shrank or diminished in 18 patients (82%). Despite the clinical/radiographical improvement, serum levels of total IgE, the key biomarker for the pharmacological response in ABPA, were unchanged. Anti-IL-5/IL-5Rα mAbs that directly target eosinophils are promising candidates for the treatment of patients with ABPA, especially those with mucus plugs in the bronchi.

Objective The clinical characteristics and chest imaging findings of viral pneumonia and several interstitial lung diseases (ILDs) overlap, and viral pneumonia may be underrecognized and misdiagnosed as certain ILDs. To clarify the frequency of viral pneumonia among patients with acute progressive clinical courses that required a differential diagnosis between ILDs and pneumonia, and to determine the most frequent ILDs misdiagnosed in cases of viral pneumonia. Patients and Methods We retrospectively analyzed patients hospitalized from 2010 to 2017 with an acute clinical course (≤30 days) who underwent bronchoalveolar lavage (BAL) for the differential diagnosis of infection and ILDs. We performed a multiplex PCR for respiratory viruses using the patients' preserved BAL fluid. The final diagnosis was made by a multidisciplinary approach and after considering the PCR results. The diagnosis at discharge was compared to the final diagnosis. Results Among the 109 patients, 53 were diagnosed with viral pneumonia. Viral pneumonia and other diseases showed some differences in symptoms and laboratory data; however, the differences were small or overlapped. Viral pneumonia was misdiagnosed on discharge as acute fibrinous organizing pneumonia, cryptogenic organizing pneumonia, or chronic eosinophilic pneumonia (AFOP/COP/CEP) (n=22), acute interstitial pneumonia (n=5), connective tissue disease-related ILDs (n=3), unclassifiable interstitial pneumonia (n=2), drug-induced ILD (n=1), and pneumonia (n=20). Conclusion Approximately half of the patients who underwent BAL had viral pneumonia. The most common ILD-related misdiagnoses were AFOP/COP/CEP. Differences in symptoms and laboratory findings between viral pneumonia and other diseases were small, and viral pneumonia should be included in the differential diagnosis when physicians encounter cases in which the abovementioned ILDs are suspected.

Background: Hypersensitivity pneumonitis (HP) is classified into nonfibrotic and fibrotic phenotypes. Patients with nonfibrotic HP often experience recurrence and develop fibrosis, whereas those with fibrotic HP have a poor prognosis. Although antigen avoidance has long been the first line of treatment for HP, its impact on prognosis has been poorly reported.Methods: Medical records of 121 patients with HP diagnosed by new diagnostic criteria of American Thoracic Society/Japanese Respiratory Society/Asociación Latinoamericana del Tórax (ATS/JRS/ALAT) guidelines and treated at our institution in Saitama, Japan, were retrospectively analysed. HP was classified into nonfibrotic and fibrotic phenotypes and six HP subtypes: summer-type, bird-related, home-related and occupational HP, humidifier lung, and hot tub lung. Achievement of reduced exposure to inciting agents was divided into complete antigen avoidance (CAA) and incomplete antigen avoidance (IAA) by HP subtype.Results: Of the 74 patients with nonfibrotic HP, 30 achieved CAA and experienced no recurrence or development of fibrosis. In the remaining 44 patients with IAA, 24 (54.5%) experienced recurrence and/or development of fibrosis. The all-cause 5-year mortality rate in the 47 patients with fibrotic HP was 47.8%. Negative prognostic factors of HP-related mortality in these patients were <50% lymphocytes in bronchoalveolar lavage (BAL) and honeycombing. Multivariate analysis showed a tendency for IAA to be related to poorer survival (hazard ratio 3.452, 95% CI 0.964–12.359, p=0.057).Conclusions: In the patients with nonfibrotic HP, CAA resulted in no recurrence or development of fibrosis and longer survival. In the patients with fibrotic HP, <50% lymphocytes in BAL and honeycombing were negative prognostic factors for mortality.

Background Empyema due to Candida species is a rare entity, and the significance of isolation of Candida species from the pleural effusion is not fully understood. Objective To elucidate the clinical features of Candida empyema. Methods We retrospectively reviewed the cases of 128 patients with culture-positive empyema. Results These 128 patients included 7 whose cause of empyema was esophago- or gastropleural fistula. Empyema was due to Candida species in 5 of the 7 patients. Primary diseases of these 5 patients were spontaneous esophageal rupture in 3 patients, esophageal rupture due to lung cancer invasion in 1 patient, and gastric ulcer perforation in 1 patient. None of these 5 patients had esophageal candidiasis. Among the 121 other patients with empyema not due to esophago- or gastropleural fistula, no patient had empyema due to Candida. Conclusion We believe that the empyema in these 5 patients was caused by normal commensal Candida species entering the pleural cavity when the fistula between the gastrointestinal tract and pleural cavity was formed. Isolation of Candida species can be an important clue for suspecting gastrointestinal tract perforation as a cause of empyema.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterised by progressive fibrosis of lung parenchyma. The histopathology of IPF exhibits temporal and spatial heterogeneity, including immature fibroblastic foci (FF) and densely collagenised fibrosis. FF serve as dynamic niches of pro-fibrotic fibroblasts and play a pivotal role in fibrosis progression and transition into dense fibrosis (DF). Here, we integrated single-cell RNA sequencing (scRNA-seq) with spatial transcriptomics to elucidate cellular heterogeneity and the novel cell type involved not only in FF formation, but also in DF development. We identified a novel myofibroblast population, WNT5A ⁺ CTHRC1 ⁺ myofibroblasts, enriched in both FF and DF regions, underscoring their pivotal role in fibrosis progression. Differential gene expression analysis revealed the activation of p21-activated kinase (PAK)2 in these fibrotic areas, including WNT5A ⁺ CTHRC1 ⁺ myofibroblasts. PAK inhibition significantly suppressed transforming growth factor-β-induced myofibroblast differentiation and collagen production in IPF-derived fibroblasts. Furthermore, in a bleomycin-induced lung fibrosis mouse model, intraperitoneal administration of the PAK inhibitor significantly attenuated fibrotic progression. This study highlights the therapeutic potential of PAK inhibition for IPF, particularly targeting pathogenic fibroblasts within both FF and DF regions. By leveraging spatial transcriptomics and scRNA-seq, we provide a comprehensive molecular and cellular atlas of FF and DF in IPF lung tissue, offering new insights into fibrosis progression and therapeutic intervention.