Daily Respiratory Research Analysis
Three impactful studies shape respiratory science and practice today: (1) a Lancet Microbe preclinical study shows a US dairy-farm H5N1 strain causes fatal infection and transmission after ocular-only exposure in ferrets, underscoring eye protection; (2) an Autophagy mechanistic study links microplastics to COPD exacerbation via mito-ROS–driven autophagy and ferroptosis; (3) a Clinical Infectious Diseases systematic review finds high prevalence of chronic pulmonary aspergillosis among TB patient
Summary
Three impactful studies shape respiratory science and practice today: (1) a Lancet Microbe preclinical study shows a US dairy-farm H5N1 strain causes fatal infection and transmission after ocular-only exposure in ferrets, underscoring eye protection; (2) an Autophagy mechanistic study links microplastics to COPD exacerbation via mito-ROS–driven autophagy and ferroptosis; (3) a Clinical Infectious Diseases systematic review finds high prevalence of chronic pulmonary aspergillosis among TB patients, advocating routine screening.
Research Themes
- Zoonotic influenza and ocular exposure risk
- Microplastics driving COPD pathophysiology via ferroptosis
- Chronic pulmonary aspergillosis burden after tuberculosis and screening
Selected Articles
1. Ocular infectivity and replication of a clade 2.3.4.4b A(H5N1) influenza virus associated with human conjunctivitis in a dairy farm worker in the USA: an in-vitro and ferret study.
Human nasal and corneal models supported replication of multiple IAVs; H5N1 did not show uniquely enhanced ocular tropism relative to H7N7 or H1N1. In serologically naive ferrets, ocular-only exposure to the H5N1 Texas/37 strain resulted in systemic, often fatal infection and transmission to cage-mates, whereas pre-existing H1N1 immunity mitigated disease and prevented onward transmission.
Impact: Demonstrates that ocular exposure alone can seed fatal and transmissible H5N1 infection, directly informing PPE and occupational safety in zoonotic outbreaks.
Clinical Implications: Reinforce strict eye protection for exposed workers (e.g., dairy farms, laboratories) and clinicians. Consider ocular exposure pathways in risk assessments and infection control guidance, and recognize that heterosubtypic immunity may mitigate severity but not necessarily prevent infection without comprehensive PPE.
Key Findings
- Human corneal and nasal tissue constructs supported replication of H5N1, H7N7, and H1N1; H5N1 did not exhibit uniquely enhanced ocular tropism.
- Ocular-only exposure to H5N1 Texas/37 in naive ferrets caused systemic, often fatal infection and transmission to cage mates.
- Pre-existing H1N1pdm09 immunity reduced disease severity after ocular exposure and prevented transmission to naive contacts.
Methodological Strengths
- Integrated in-vitro human tissue constructs with in-vivo ferret infection models across multiple exposure routes.
- Compared multiple IAV strains and quantified replication kinetics and host innate responses.
Limitations
- Exact ferret sample sizes and detailed statistical power are not provided in the abstract.
- Preclinical models may not fully capture human ocular exposure dynamics and clinical outcomes.
Future Directions: Quantify human ocular exposure risks across settings; evaluate vaccine/antiviral protection against ocular inoculation; refine PPE guidance and implement occupational surveillance in affected industries.
BACKGROUND: The human eye represents a potential site of influenza A virus (IAV) replication, and an entry point for the virus to reach the respiratory tract. The frequent detection of conjunctivitis among farm workers with confirmed infection with clade 2.3.4.4b A(H5N1) IAV from this ongoing outbreak represents an atypical disease presentation for this virus subtype. We aimed to investigate whether the occurrence of ocular complications reported following clade 2.3.4.4b A(H5N1) virus infection was associated with an enhanced capacity of this virus to replicate in mammalian ocular tissue and cause infection following ocular exposure. METHODS: Primary human nasal and corneal tissue constructs were infected with A(H5N1) A/Texas/37/2024 (Texas/37), A(H1N1)pdm09 A/Nebraska/14/2019 (Neb/14), and A(H7N7) A/Netherlands/219/2003 (NL/219) viruses (multiplicity of infection [MOI] of 0·01-0·02, 33°C). Corneal tissue constructs were also infected with an expanded panel of IAVs (Texas/37, A[H5N1] A/Michigan/90/2024 [MI/90], A[H5N1] A/Chile/25945/2023 [Chile/25945], NL/219, A/Netherlands/230/2003 [NL/230], and Neb/14; MOI of 0·01, 37°C). In-vitro infections of tissue constructs were used to assess replication kinetics by infectious virus titration. Induction of innate host antiviral responses in infected corneal tissue constructs was assessed by PCR array (MOI of 2·00, 37°C). Ferrets (serologically naive or pre-immune to A[H1N1]pdm09 virus) were inoculated by the ocular route with Texas/37 A(H5N1) virus-using a liquid inoculum (10⁶ plaque forming units [PFU]), aerosol inhalation (15-16 PFU), or ocular-only aerosol exposure (18-132 PFU)-to assess pathogenicity and tropism of the virus following different exposure routes.
2. Microplastics exacerbate ferroptosis via mitochondrial reactive oxygen species-mediated autophagy in chronic obstructive pulmonary disease.
Human COPD lungs contained higher microplastic loads (notably PS-MPs) and iron; PS-MPs induced mito-ROS, lysosome biogenesis/acidification, ferritinophagy, and autophagy-dependent ferroptosis, intensifying inflammation and triggering AECOPD in models. Targeting mito-ROS or ferroptosis attenuated inflammation and exacerbations.
Impact: Reveals a mechanistic link between environmental microplastics and COPD exacerbation via autophagy-dependent ferroptosis, opening therapeutic avenues (mito-ROS scavengers, ferroptosis inhibitors) and informing environmental policy.
Clinical Implications: Suggests considering ferroptosis-modulating and mito-ROS–targeted strategies in COPD exacerbation management, alongside minimizing microplastic exposure. Supports biomarker development (e.g., iron, ferroptosis signatures) for risk stratification.
Key Findings
- COPD lung tissues harbored significantly higher levels of microplastics (especially PS-MPs) and iron than controls (Py-GCMS).
- PS-MPs induced mito-ROS, lysosome biogenesis/acidification, ferritinophagy and autophagy-dependent ferroptosis, driving inflammation and AECOPD in vitro and in vivo.
- Mitochondria-targeted ROS scavenging or ferroptosis inhibition reduced inflammation and ameliorated PS-MP–induced AECOPD.
Methodological Strengths
- Human tissue quantification (Py-GCMS) integrated with in vivo mouse models and mechanistic in vitro assays.
- Causal rescue experiments using mito-ROS scavengers and ferroptosis inhibitors.
Limitations
- Human sample sizes and exposure quantification relative to real-world inhalation are not detailed in the abstract.
- Translational relevance requires clinical validation of ferroptosis-targeted interventions in COPD.
Future Directions: Prospective clinical studies to validate ferroptosis/mito-ROS biomarkers and test ferroptosis-modulating therapies in COPD; environmental interventions to reduce microplastic exposure and assess respiratory benefits.
Microplastics (MPs) induce mitochondrial dysfunction and iron accumulation, contributing to mitochondrial macroautophagy/autophagy and ferroptosis, which has increased susceptibility to the exacerbation of chronic obstructive pulmonary disease (COPD); however, the underlying mechanism remains unclear. We demonstrated that MPs intensified inflammation in COPD by enhancing autophagy-dependent ferroptosis (ADF) in vitro and in vivo. In the lung tissues of patients with COPD, the concentrations of MPs, especially polystyrene microplastics (PS-MPs), were significantly higher than that of the control group, as detected by pyrolysis gas chromatography mass spectrometry (Py-GCMS), with increased iron accumulation. The exposure to PS-MPs, 2 μm in size, resulted in their being deposited in the lungs of COPD model mice detected by optical in vivo imaging, and observed in bronchial epithelial cells traced by GFP-labeled PS-MPs. There were mitochondrial impairments accompanied by mitochondrial reactive oxygen species (mito-ROS) overproduction and significantly increased levels of lysosome biogenesis and acidification in pDHBE cells with PS-MP stimulation, triggering occurrence of ferritinophagy and enhancing ADF in COPD, which triggered acute exacerbation of COPD (AECOPD). Reestablishing autophagy-dependent ferroptosis via mitochondria-specific ROS scavenging or ferroptosis inhibition alleviated excessive inflammation and ameliorated AECOPD induced by PS-MPs.
3. A Systematic Review of Chronic Pulmonary Aspergillosis Among Patients Treated for Pulmonary Tuberculosis.
Across 22 studies (n=2884), pooled CPA prevalence among TB patients was 9% during treatment and 13% post-treatment; in those with persistent respiratory symptoms, prevalence reached 20% and 48%, respectively. Symptom status and timing of assessment were key predictors, supporting routine CPA screening within TB programs.
Impact: Quantifies a substantial CPA burden among TB survivors, providing actionable evidence to integrate CPA screening into TB care pathways to prevent post-TB lung disease.
Clinical Implications: Implement CPA screening (serology, imaging, mycology) during and after TB treatment, especially in patients with persistent respiratory symptoms, to initiate antifungal therapy and reduce long-term respiratory impairment.
Key Findings
- Pooled CPA prevalence among TB patients: 9% during treatment and 13% post-treatment.
- Among TB patients with persistent respiratory symptoms, CPA prevalence was 20% during treatment and 48% post-treatment.
- Meta-regression identified symptom status and timing of CPA assessment as significant predictors of prevalence.
Methodological Strengths
- Comprehensive multi-database search with predefined inclusion criteria and meta-regression.
- Random-effects meta-analysis across 22 studies with subgroup analyses by timing and symptoms.
Limitations
- Diagnostic heterogeneity of CPA across studies may influence pooled estimates.
- Geographical and healthcare setting variability may limit generalizability.
Future Directions: Standardize CPA diagnostic algorithms within TB programs and evaluate cost-effectiveness of routine screening; conduct prospective cohorts to define outcomes with early antifungal treatment.
BACKGROUND: Tuberculosis (TB) is a major global health concern, with long-term complications persisting even after successful treatment. Chronic pulmonary aspergillosis (CPA) is a progressive fungal disease that frequently develops in TB survivors, contributing to post-TB lung disease. The true burden of CPA among patients with TB remains unclear due to diagnostic challenges and limited data. We aimed to estimate the prevalence of CPA among patients with prior or concurrent TB. METHODS: We conducted a systematic search in PubMed, Cochrane Library, Web of Science, and Science Direct through 10 January 2025. Eligible cohort and cross-sectional studies reported CPA prevalence in patients diagnosed with TB based on clinical symptoms, radiographic abnormalities, and microbiological evidence. Three reviewers screened 1575 unique studies, assessed 118 full texts, and included 22 studies (2884 patients). We conducted a meta-analysis using a random-effects model to estimate pooled CPA prevalence, with subgroup and meta-regression analyses exploring factors influencing CPA burden. RESULTS: CPA prevalence varied by timing of assessment and symptom status. Among all patients with TB, CPA prevalence was 9% (95% confidence interval [CI]: 6%-12%) during treatment and 13% (95% CI: 6%-27%) posttreatment. Among patients with persistent respiratory symptoms, CPA prevalence was 20% during treatment and 48% (95% CI: 36%-61%) posttreatment. Meta-regression identified symptom status and timing of CPA assessment as significant predictors of CPA prevalence. CONCLUSIONS: The high CPA burden among TB survivors, particularly those with persistent symptoms, underscores the need for routine CPA screening in TB programs. Early detection and targeted interventions could reduce respiratory complications and improve patient outcomes.