Dang, Hong

Abstract Rationale Inflammation is central to chronic obstructive pulmonary disease (COPD) pathogenesis but incompletely represented in COPD prognostic models. The neutrophil-to-lymphocyte ratio (NLR) is a readily available inflammatory biomarker. Objectives To explore the associations of NLR with smoking status, clinical features of COPD, and future adverse outcomes. Methods We analyzed NLR calculated from the complete blood count of participants who currently or formerly smoked (n = 2,624) and tobacco-naive control subjects (n = 187) in the SPIROMICS multicenter observational cohort study. We assessed the stability of NLR at 6 weeks and 1 year, the association with select blood biomarkers, and the impact of smoking on NLR and cell counts. We stratified participants by NLR quartiles to compare cross-sectional clinical features at enrollment, prospectively observed exacerbations at 1 year, and mortality during longitudinal follow up. Results Higher NLR quartiles were broadly associated with more severe clinical features of COPD. NLR values were repeatable at 6 weeks (intraclass correlation coefficient, 0.74) and 1 year (intraclass correlation coefficient, 0.62). The impact of smoking on NLR varied with the severity of airflow limitation, mediated by an interaction between smoking, forced expiratory volume in 1 second percent predicted, and neutrophil counts but not lymphocyte counts. The highest NLR quartile (>3.11) was associated with an increased risk of exacerbation over 1 year (adjusted odds ratio, 1.51; 95% confidence interval, 1.18, 1.92) and increased risk of mortality (adjusted hazard ratio, 1.41; 95% confidence interval, 1.20, 1.66) compared with quartiles 1–3. Conclusions Elevated NLR in stable COPD is a widely available biomarker associated with increased risk for exacerbation and death. The impact of cigarette smoking on NLR varies with disease severity.

Abstract Rationale: Primary ciliary dyskinesia (PCD) is a heterogeneous, rare genetic disorder characterized by dysfunctional motile cilia. PCD pulmonary manifestations include impaired airway mucociliary clearance, mucus obstruction, recurrent infection, and bronchiectasis (BE). Notably, thoracic imaging studies indicate that alveolar atelectasis is more prevalent in children with PCD than in age-matched children with cystic fibrosis (CF). However, morphologic and molecular analyses of the site of initiation and progression of PCD airway disease and relationships to PCD alveolar disease have not been reported. In this study, we analyzed region-specific morphologic and molecular characterizations of airway epithelia and alveolar regions in PCD lungs excised at transplantation to address these questions. Methods: Nine PCD lungs and seven non-diseased control lungs were included in the morphometric studies. Bronchi and proximal and distal bronchioles were defined using unique morphologic structures, and distal airway secretory cell (DASC) markers were used to differentiate between proximal and distal bronchioles. Morphologic characteristics of airway epithelia and luminal mucus were quantitated by histology, immunohistochemistry, and RNA in situ hybridization. Spatial transcriptomic technologies (GeoMx) characterized region-specific transcript expression in three airway epithelial regions (bronchi, proximal bronchioles, and distal bronchioles), intraluminal mucus plugs, and alveolar regions of PCD compared to control lungs. Finally, pulmonary function data from a cohort of PCD subjects were analyzed to investigate correlations between alveolar morphologic findings and alveolar gas exchange function, i.e. diffusing capacity for carbon monoxide (DLCO). Results: PCD bronchi and proximal bronchioles exhibited ectasia, characterized by increased MUC5AC and MUC5B-producing cells, mucus plugs containing MUC5AC and MUC5B mucins infiltrated by neutrophils, and epithelial gene signatures associated with ectasia. In contrast, PCD distal bronchioles were not ectatic and exhibited MUC5B-dominant DASCs, mucus plugs containing selectively MUC5B mucin infiltrated by mixture of neutrophils and macrophages, and gene signatures suggestive of impaired ciliogenesis. Molecular analysis revealed upregulation of pathways associated with muco-inflammation, antimicrobial defense, and the innate immune system routinely in PCD airway epithelia. IL-1β gene signatures were observed in both PCD airway and alveolar epithelia, whereas interferon-stimulated gene signatures were restricted to airway epithelia. Transcriptomic and morphologic analyses suggested that PCD alveolar disease was initiated by distal bronchiolar obstruction, associated with chronic microatelectasis, progressive loss of alveolar epithelial type 2 (AT2) cells, and eventual non-resolving fibrosis. A significant percentage (28%) of people with PCD exhibited reduced DLCO. Conclusions: PCD airway disease is manifest by distinct profiles of proximal vs distal bronchiolar disease associated with microatelectatic and fibrotic alveolar disease.

A subset of individuals who recover from coronavirus disease 2019 (COVID-19) develop post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC), but the mechanistic basis of PASC-associated lung abnormalities suffers from a lack of longitudinal tissue samples. The mouse-adapted SARS-CoV-2 strain MA10 produces an acute respiratory distress syndrome in mice similar to humans. To investigate PASC pathogenesis, studies of MA10-infected mice were extended from acute to clinical recovery phases. At 15 to 120 days after virus clearance, pulmonary histologic findings included subpleural lesions composed of collagen, proliferative fibroblasts, and chronic inflammation, including tertiary lymphoid structures. Longitudinal spatial transcriptional profiling identified global reparative and fibrotic pathways dysregulated in diseased regions, similar to human COVID-19. Populations of alveolar intermediate cells, coupled with focal up-regulation of profibrotic markers, were identified in persistently diseased regions. Early intervention with antiviral EIDD-2801 reduced chronic disease, and early antifibrotic agent (nintedanib) intervention modified early disease severity. This murine model provides opportunities to identify pathways associated with persistent SARS-CoV-2 pulmonary disease and test countermeasures to ameliorate PASC.