Brandie D. Wagner

Introduction: Dysregulated protease activity contributes to airway inflammation and tissue remodeling in cystic fibrosis (CF); however, the role of the lysosomal cysteine protease Cathepsin B (CTSB) remains incompletely defined. This cross‐sectional study investigates relationships between pro‐CTSB and mature CTSB activity with CF‐specific pathogens and airway inflammation in children with and without CF. Methods: Bronchoalveolar lavage fluid (BALF) was collected from clinically indicated bronchoscopies in children ( N = 52 CF, N = 161 non‐CF). CTSB was interrogated using ELISA, fluorogenic activity assay, and Western blot analysis to distinguish pro‐ and mature CTSB. Total bacterial and total fungal load (TFL) were quantified by quantitative polymerase chain reaction, and community composition was determined by 16S bacterial and 18S fungal sequencing. Concentrations of proinflammatory cytokines and neutrophil elastase (NE) were measured via Luminex multiplatform and a spectrophotometric assay, respectively. Analyses included Spearman's rank correlations and Wilcoxon rank‐based tests. Results: Pro‐CTSB and CTSB activity were significantly ( p < 0.01) elevated in CF BALF and in samples with a positive Staphylococcus aureus airway culture. Pro‐CTSB concentrations correlated with staphylococcal relative abundance (RA, = 0.25, p < 0.02) and reduced bacterial diversity ( = −0.41, p < 0.01). Mature CTSB activity correlated with TFL ( = 0.50, p < 0.05) and Aspergillus spp. RA ( = 0.36, p < 0.04). Western blot analysis confirmed pro‐CTSB expression and mature CTSB in BALF with measurable activity. Both CTSB measures correlated strongly with NE and proinflammatory cytokines ( ≥ 0.47, p < 0.001). Pro‐CTSB concentrations negatively correlated with FEV1/FVC measurements in CF ( = −0.32, p = 0.05). Conclusions: BALF CTSB concentration may serve as a CF‐specific biomarker of infection‐related inflammation and obstructive lung disease driven by specific pathogen interactions.

Microbial communities manifest differently across ecological niches of the body; structural and functional heterogeneity, including local physiology, within each gastrointestinal (GI) compartment, ...

Accurately distinguishing lower respiratory tract infection (LRTI) from incidental pathogen carriage (IPC) is clinically challenging. The host immunologic and microbial factors that define the states of LRTI and IPC are poorly understood. We performed host-microbe metatranscriptomic profiling of tracheal aspirate from 326 mechanically ventilated children with clinically adjudicated LRTI (n=207), IPC (n=70), or non-infectious acute respiratory illnesses (n=49). In the airway microbiome, LRTI was characterized by reduced alpha diversity and taxonomic richness, while IPC was characterized greater total bacterial abundance, enrichment in respiratory anaerobes and increased metabolic activity. In terms of host response, patients with LRTI exhibited a distinct lower airway transcriptional signature of innate and adaptive immune activation compared to those with IPC, who had similar transcriptional profiles as uninfected controls. Mediation analyses suggested that the airway microbiome influences the host response to pathogens. An integrated host-microbe metatranscriptomic classifier discriminated LRTI from IPC and controls with an AUC=0.89 (95% confidence interval (CI) 0.85-0.92). The single gene FABP4, when combined with alpha diversity, performed similarly, and FABP4 protein alone achieved an AUC=0.88 (95% CI 0.82-0.93). Together, our findings reveal distinct ecological and immunologic archetypes that define LRTI and IPC, and support data-driven, biology-informed LRTI diagnostics that incorporate host and microbe.

Objectives To assess whether increasing levels of hospital stress—measured by intensive care unit (ICU) bed occupancy (primary), ventilators in use and emergency department (ED) overflow—were associated with decreasing COVID-19 ICU patient survival in Colorado ICUs during the pre-Delta, Delta and Omicron variant eras. Design A retrospective cohort study using discrete-time survival models, fit with generalised estimating equations. Setting 34 hospital systems in Colorado, USA, with the highest patient volume ICUs during the COVID-19 pandemic. Participants 9196 non-paediatric SARS-CoV-2 patients in Colorado hospitals admitted once to an ICU between 1 August 2020 and 1 March 2022 and followed for 28 days. Outcome measures Death or discharge to hospice. Results For Delta-era COVID-19 ICU patients in Colorado, the odds of death were estimated to be 26% greater for patients exposed every day of their ICU admission to a facility experiencing its all-era 75th percentile ICU fullness or above, versus patients exposed for none of their days (OR: 1.26; 95% CI: 1.04 to 1.54; p=0.0102), adjusting for age, sex, length of ICU stay, vaccination status and hospital quality rating. For both Delta-era and Omicron-era patients, we also detected significantly increased mortality hazard associated with high ventilator utilisation rates and (in a subset of facilities) states of ED overflow. For pre-Delta-era patients, we estimated relatively null or even protective effects for the same fullness exposures, something which provides a meaningful contrast to previous studies that found increased hazards but were limited to pre-Delta study windows. Conclusions Overall, and especially during the Delta era (when most Colorado facilities were at their fullest), increasing exposure to a fuller hospital was associated with an increasing mortality hazard for COVID-19 ICU patients.

Background: Tobramycin inhalation solution (TIS) and chronic azithromycin (AZ) have known clinical benefits for children with CF, likely due to antimicrobial and anti-inflammatory activity. The effects of chronic AZ in combination with TIS on the airway microbiome have not been extensively investigated. Oropharyngeal swab samples were collected in the OPTIMIZE multicenter, randomized, placebo-controlled trial examining the addition of AZ to TIS in 198 children with CF and early P. aeruginosa infection. Bacterial small subunit rRNA gene community profiles were determined. The effects of TIS and AZ were assessed on oropharyngeal microbial diversity and composition to uncover whether effects on the bacterial community may be a mechanism of action related to the observed changes in clinical outcomes. Results: Substantial changes in bacterial communities (total bacterial load, diversity and relative abundance of specific taxa) were observed by week 3 of TIS treatment for both the AZ and placebo groups. On average, these shifts were due to changes in non-traditional CF taxa that were not sustained at the later study visits (weeks 13 and 26). Bacterial community measures did not differ between the AZ and placebo groups. Conclusions: This study provides further evidence that the mechanism for AZ’s effect on clinical outcomes is not due solely to action on airway microbial composition.

Background: Repository corticotrophin injection (RCI, Acthar Gel) and intravenous methylprednisolone (IVMP) improve the rate but not the extent of visual recovery following acute optic neuritis. RCI has adrenal-stimulating and melanocortin receptor-stimulating properties that may endow it with unique anti-inflammatory properties relative to IVMP. Methods: Individuals with acute optic neuritis of less than 2 weeks duration were prospectively enrolled and randomized 1:1 to receive either RCI or IVMP. Peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell plus inner plexiform layer thickness (GC + IPL) were serially evaluated by OCT. In addition, patient-reported outcomes (PROs) for changes in fatigue, mood, visual function, depression, and quality of life (QOL) were measured, and high and low contrast visual acuity were recorded. Results: Thirty-seven subjects were enrolled (19 RCI; 18 IVMP); the average time from symptom to treatment was 8.8 days. At 6 months, there was no difference in the primary outcome: loss of average pRNFL thickness in the affected eye (RCI vs IVMP: −13.1 vs −11.7 µm, P = 0.88) 6 months after randomization. Additional outcomes also showed no difference between treatment groups: 6-month attenuation of GC + IPL thickness (RCI vs IVMP: −13.8 vs −12.0 µm, P = 0.58) and frequency of pRNFL swelling at 1 month (RCI vs IVMP: 63% vs 72%, P = 0.73) and 3 months (RCI vs IVMP: 26% vs 31%, P = 0.99). Both treatments resulted in improvement in visual function and PROs. Conclusions: Treatment of acute optic neuritis with RCI or IVMP produced no clinically meaningful differences in optic nerve structure or visual function.