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Daily Report

Daily Respiratory Research Analysis

04/13/2025
3 papers selected
3 analyzed

Three impactful respiratory studies stood out: a Bayesian meta-analysis shows machine listening using overnight audio can diagnose obstructive sleep apnea with accuracy comparable to home sleep tests; a mechanistic Cell Reports study identifies alveolar macrophages as central defenders preventing severe coronavirus pneumonia; and a prospective multicenter study demonstrates tumor-agnostic ctDNA can detect minimal residual disease and predict recurrence after curative treatment for NSCLC.

Summary

Three impactful respiratory studies stood out: a Bayesian meta-analysis shows machine listening using overnight audio can diagnose obstructive sleep apnea with accuracy comparable to home sleep tests; a mechanistic Cell Reports study identifies alveolar macrophages as central defenders preventing severe coronavirus pneumonia; and a prospective multicenter study demonstrates tumor-agnostic ctDNA can detect minimal residual disease and predict recurrence after curative treatment for NSCLC.

Research Themes

  • AI-enabled respiratory diagnostics
  • Innate immunity in viral pneumonia
  • Liquid biopsy for postoperative surveillance in lung cancer

Selected Articles

1. Alveolar macrophages critically control infection by seasonal human coronavirus OC43 to avoid severe pneumonia.

85.5Level VBasic/Mechanistic research
Cell reports · 2025PMID: 40222012

In a mouse model of seasonal coronavirus OC43, loss of alveolar macrophages precipitated severe COVID-19-like pneumonia with neutrophil influx, NET formation, and cytokine amplification. Alveolar macrophages directly phagocytosed virus to limit spread; in their absence, TLR-driven chemokines fueled pathology, indicating AMs are central protectors against coronavirus lower respiratory disease.

Impact: This work delineates a macrophage-centric mechanism preventing severe coronavirus pneumonia, reframing emphasis from adaptive immunity to alveolar macrophage function. It informs therapeutic strategies that preserve or augment AM activity and modulate NET-driven pathology.

Clinical Implications: Therapies preserving alveolar macrophage function (e.g., avoiding unnecessary macrophage-toxic regimens), targeted modulation of TLR signaling or NETs, and macrophage-supportive interventions could reduce coronavirus pneumonia severity.

Key Findings

  • Alveolar macrophage deficiency converted otherwise mild HCoV-OC43 infection into severe COVID-19-like pneumonia in mice.
  • AMs limited infection by phagocytosing HCoV-OC43; in their absence, TLR-dependent chemokines drove neutrophil infiltration and NET release.
  • Innate sensing pathways and adaptive immune cells were not essential for protection against HCoV-OC43, highlighting AMs as central defenders.

Methodological Strengths

  • In vivo mechanistic model with cellular and molecular readouts (phagocytosis, NETs, cytokines).
  • Clear causal inference via macrophage deficiency to demonstrate necessity of AMs.

Limitations

  • Mouse OC43 model may not fully recapitulate human SARS-CoV-2 pathogenesis.
  • Specific macrophage depletion approaches can have off-target effects; human validation is needed.

Future Directions: Validate AM-centric protection in human tissues or cohorts; test interventions enhancing AM function or modulating TLR/NET pathways in translational models.

Seasonal coronaviruses, similar to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), only cause severe respiratory symptoms in a small fraction of infected individuals. However, the host factors that determine the variable responses to coronavirus infection remain unclear. Here, we use seasonal human coronavirus OC43 (HCoV-OC43) infection as an asymptomatic model that triggers both innate and adaptive immune responses in mice. Interestingly, innate sensing pathways as well as adaptive immune cells are not essential in protection against HCoV-OC43. Instead, alveolar macrophage (AMΦ) deficiency in mice results in COVID-19-like severe pneumonia post HCoV-OC43 infection, with abundant neutrophil infiltration, neutrophil extracellular trap (NET) release, and exaggerated pro-inflammatory cytokine production. Mechanistically, AMΦ efficiently phagocytose HCoV-OC43, effectively blocking virus spread, whereas, in their absence, HCoV-OC43 triggers Toll-like receptor (TLR)-dependent chemokine production to cause pneumonia. These findings reveal the central role of AMΦ in defending against seasonal HCoV-OC43 with clinical implications for human immunopathology associated with coronavirus infection.

2. Machine Listening for OSA Diagnosis: A Bayesian Meta-Analysis.

83Level IMeta-analysis
Chest · 2025PMID: 40220991

Across 16 studies (41 models), machine listening using overnight audio achieved pooled sensitivity of 90.3% and specificity of 86.7% for OSA, comparable to common home sleep tests and superior to STOP-Bang screening. Performance was robust across smartphone vs professional microphones; higher sampling frequency and non-contact microphones improved sensitivity.

Impact: This high-quality meta-analysis substantiates AI-based, contactless OSA diagnostics as clinically credible, enabling scalable pre-diagnostic screening and triage beyond sleep labs.

Clinical Implications: Machine listening can augment or pre-screen OSA referrals, reduce reliance on polysomnography, and expand access via consumer devices; external validation and integration into clinical pathways are needed.

Key Findings

  • Pooled diagnostic accuracy for OSA: sensitivity 90.3%, specificity 86.7%; diagnostic OR 60.8.
  • Accuracy comparable between home smartphone recordings and laboratory microphones; deep learning vs traditional ML performed similarly.
  • Higher audio sampling frequency and non-contact microphones were associated with increased sensitivity; no evident publication bias.

Methodological Strengths

  • Bayesian bivariate meta-analysis with meta-regression and selection model to assess publication bias.
  • Rigorous study selection with masked reviewers and standardized diagnostic accuracy frameworks.

Limitations

  • Heterogeneity in datasets, model evaluation (train-test split vs k-fold), and AHI thresholds.
  • Potential optimism in train-test split evaluations; limited external validation across diverse populations.

Future Directions: Prospective, device-agnostic external validations; integration trials in primary care to assess referral reduction, cost-effectiveness, and patient-centered outcomes.

BACKGROUND: Among 1 billion patients worldwide with OSA, 90% remain undiagnosed. The main barrier to diagnosis is the overnight polysomnogram, which requires specialized equipment, skilled technicians, and inpatient beds available only in tertiary sleep centers. Recent advances in artificial intelligence (AI) have enabled OSA detection using breathing sound recordings. RESEARCH QUESTION: What is the diagnostic accuracy of and how can we optimize machine listening for OSA? STUDY DESIGN AND METHODS: PubMed, Embase, Scopus, Web of Science, and IEEE Xplore databases were systematically searched. Two masked reviewers selected studies comparing the patient-level diagnostic performance of AI approaches using overnight audio recordings vs conventional diagnosis (apnea-hypopnea index) using a train-test split or k-fold cross-validation. Bayesian bivariate meta-analysis and meta-regression were performed. Publication bias was assessed by using a selection model. Risk of bias and evidence quality were assessed by using the Quality Assessment of Diagnostic Accuracy Studies-2 and the Grading of Recommendations, Assessment, Development, and Evaluation tools. RESULTS: From 6,254 records, 16 studies (41 models) trained on 4,864 participants and tested on 2,370 participants were included. No study had a high risk of bias. Machine listening achieved a pooled sensitivity (95% credible interval) of 90.3% (86.9%-93.1%), a specificity of 86.7% (83.1%-89.7%), a diagnostic OR of 60.8 (39.4-99.9), and positive and negative likelihood ratios of 6.78 (5.34-8.85) and 0.113 (0.079-0.152), respectively. At apnea-hypopnea index cutoffs of ≥ 5, ≥ 15, and ≥ 30 events per hour, sensitivities were 94.3% (90.3%-96.8%), 86.3% (80.1%-90.9%), and 86.3% (79.2%-91.1%); and specificities were 78.5% (68.0%-86.9%), 87.3% (81.8%-91.3%), and 89.5% (84.8%-93.3%). Meta-regression identified increased sensitivity for the following: higher audio sampling frequencies, non-contact microphones, higher OSA prevalence, and train-test split model evaluation. Accuracy was equal regardless of home smartphone vs in-laboratory professional microphone recordings, deep learning vs traditional machine learning, and variations in age and sex. Publication bias was not evident, and the evidence was of high quality. INTERPRETATION: In this study, machine listening achieved excellent diagnostic accuracy, superior to the STOP-Bang (snoring, tiredness, observed apnea, BP, BMI, age, neck size, gender) questionnaire and comparable to common home sleep tests. Digital medicine should be further explored and externally validated for accessible and equitable OSA diagnosis. CLINICAL TRIAL REGISTRATION: PROSPERO database; No.: CRD42024534235; URL: https://www.crd.york.ac.uk/PROSPERO/).

3. ctDNA can detect minimal residual disease in curative treated non-small cell lung cancer patients using a tumor agnostic approach.

75Level IICohort
Lung cancer (Amsterdam, Netherlands) · 2025PMID: 40220718

In a prospective multicenter cohort (n=45), tumor-agnostic ctDNA detected after curative therapy predicted recurrence and shorter RFS in NSCLC. A single sample at 4.5–7.5 months identified MRD in 50% of patients who later recurred, with strongest associations in those receiving radiotherapy/CRT, underscoring the importance of timing.

Impact: Demonstrates real-world feasibility of tumor-agnostic ctDNA MRD to risk-stratify curatively treated NSCLC and informs optimal post-treatment sampling windows by modality.

Clinical Implications: Post-treatment ctDNA can guide surveillance intensity and adjuvant/early salvage strategies; sampling at 4.5–7.5 months may be particularly informative after radiotherapy/CRT.

Key Findings

  • Post-treatment ctDNA positivity was associated with increased recurrence risk and shorter recurrence-free survival.
  • A single ctDNA sample at 4.5–7.5 months (Follow-up 2) identified MRD in 50% of patients who later recurred.
  • In radiotherapy/CRT-treated patients, ctDNA detection at Follow-up 2, but not 0.5–4.5 months, was significantly linked to shorter RFS.

Methodological Strengths

  • Prospective national multicenter design with predefined landmark sampling time points.
  • Use of CAPP-seq with a tumor-agnostic panel enabling broad applicability.

Limitations

  • Small sample size limits precision and sensitivity estimates; single-country cohort.
  • Observational design without interventional adaptation based on ctDNA; limited long-term follow-up detail.

Future Directions: Larger, modality-stratified validation cohorts and interventional trials testing ctDNA-guided adjuvant/escalation strategies; define assay thresholds and harmonize timing by treatment.

BACKGROUND: Circulating tumor DNA (ctDNA) has the potential to become a reliable biomarker for identifying minimal residual disease (MRD) and predicting recurrence in patients with non-small cell lung cancer (NSCLC) following curative treatment. However, there is a lack of studies that investigate the clinical validity of ctDNA using a tumor-agnostic approach, which can provide significant clinical benefits. METHODS: We analyzed samples from 45 NSCLC patients recruited in a prospective national multicenter study, all of whom had undergone curative treatment. A total of 38 pre-treatment plasma samples and 76 post-treatment plasma samples were examined using a commercially available cancer personalized profiling by deep sequencing (CAPP-seq) strategy, and a tumor-agnostic approach. Post-treatment samples were collected at two distinct landmark time points: Follow-up 1 (0.5-4.5 months post-treatment) and Follow-up 2 (4.5-7.5 months post-treatment). RESULTS: Detectable ctDNA post-treatment was significantly associated with increased risk of tumor recurrence and shorter recurrence-free survival (RFS). Using only a single blood sample taken from Follow-up 2, we correctly identified MRD in 50% of the patients who later experienced recurrence. However, subgroup analysis further revealed that in patients treated with radiotherapy or chemoradiotherapy (CRT), ctDNA detection was significantly linked to shorter RFS in the MRD analysis from Follow-up 2, but not in the MRD analysis from Follow-up 1. CONCLUSION: These findings suggest that post-treatment ctDNA, detected using a tumor-agnostic approach, is a reliable biomarker for predicting recurrence in NSCLC patients following curative treatment. However, the optimal timing for blood sampling to detect MRD appears to depend on the type of curative treatment received.