Nasal lavage microbiome, but not nasal swab microbiome, correlates with sinonasal inflammation in children with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is characterized by highly viscous mucus obstructing the lower and upper airways, chronic neutrophil inflammation and infection resulting not only in lung destruction but also in paranasal sinus involvement. The pathogenesis of CF-associated chronic rhinosinusitis (CRS) is still not well understood, and it remains unclear how the microbiome in the upper airways (UAW) influences paranasal sinus inflammation.

METHODS

In a cross-sectional study in pediatric patients with CF under stable disease conditions, we examined the microbiome in relation to inflammation by comparing nasal swabs (NS) and nasal lavage (NL) as two UAW sampling methods. The microbiota structure of both NS and NL was determined by 16S rRNA gene amplicon sequencing. In addition, pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) and proteases (SLPI, TIMP-1, NE/A1-AT complex) as well as neutrophil elastase activity were measured in NL.

RESULTS

Simultaneous NS and NL samples were collected from 36 patients with CF (age range: 7 - 19 years). The microbiome of NS samples was shown to be significantly lower in α-diversity and evenness compared to NL samples. NS samples were particularly found to be colonized with Staphylococcus species. NL microbiome was shown to correlate much better with the sinonasal inflammation status than NS microbiome. Especially the detection of Moraxella in NL was associated with increased inflammatory response.

CONCLUSION

Our results show that the NL microbiome reflects sinonasal inflammation better than NS and support NL as a promising tool for simultaneous assessment of the UAW microbiome and inflammation in children with CF.

Macrophage PD-1 associates with neutrophilia and reduced bacterial killing in early cystic fibrosis airway disease

BACKGROUND

Macrophages are the major resident immune cells in human airways coordinating responses to infection and injury. In cystic fibrosis (CF), neutrophils are recruited to the airways shortly after birth, and actively exocytose damaging enzymes prior to chronic infection, suggesting a potential defect in macrophage immunomodulatory function. Signaling through the exhaustion marker programmed death protein 1 (PD-1) controls macrophage function in cancer, sepsis, and airway infection. Therefore, we sought to identify potential associations between macrophage PD-1 and markers of airway disease in children with CF.

METHODS

Blood and bronchoalveolar lavage fluid (BALF) were collected from 45 children with CF aged 3 to 62 months and structural lung damage was quantified by computed tomography. The phenotype of airway leukocytes was assessed by flow cytometry, while the release of enzymes and immunomodulatory mediators by molecular assays.

RESULTS

Airway macrophage PD-1 expression correlated positively with structural lung damage, neutrophilic inflammation, and infection. Interestingly, even in the absence of detectable infection, macrophage PD-1 expression was elevated and correlated with neutrophilic inflammation. In an in vitro model mimicking leukocyte recruitment into CF airways, soluble mediators derived from recruited neutrophils directly induced PD-1 expression on recruited monocytes/macrophages, suggesting a causal link between neutrophilic inflammation and macrophage PD-1 expression in CF. Finally, blockade of PD-1 in a short-term culture of CF BALF leukocytes resulted in improved pathogen clearance.

CONCLUSION

Taken together, these findings suggest that in early CF lung disease, PD-1 upregulation associates with airway macrophage exhaustion, neutrophil takeover, infection, and structural damage.

Changes in Microbiome Dominance Are Associated With Declining Lung Function and Fluctuating Inflammation in People With Cystic Fibrosis

Airway inflammation and microbiome dysbiosis are hallmarks of cystic fibrosis (CF) lung disease. However, longitudinal studies are needed to decipher which factors contribute to the long-term evolution of these key features of CF. We therefore evaluated the relationship between fluctuation in microbiome and inflammatory parameters in a longitudinal study including a short- (1-year) and a long-term (3+ years) period. We collected 118 sputum samples from 26 CF adult patients and analyzed them by 16S rRNA gene sequencing. We measured the levels of inflammatory cytokines, neutrophil elastase, and anti-proteinases; lung function (FEV1% predicted); and BMI. The longitudinal evolution was analyzed based on (i) the rates of changes; (ii) the intra-patient stability of the variables; and (iii) the dependency of the rates of changes on the baseline values. We observed that the diversity of the microbiome was highly variable over a 1-year period, while the inflammatory markers showed a slower evolution, with significant changes only observed in the 3+ year cohort. Further, the degree of fluctuation of the biomass and the dominance of the microbiome were associated with changes in inflammatory markers, especially IL-1β and IL-8. This longitudinal study demonstrates for the first time that the long-term establishment and periodical variation of the abundance of a dominant pathogen is associated with a more severe increase in inflammation. This result indicates that a single time point or 1-year study might fail to reveal the correlation between microbial evolution and clinical degradation in cystic fibrosis.

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples

Proteases are regulators of countless physiological processes and the precise investigation of their activities remains an intriguing biomedical challenge. Among the ~600 proteases encoded by the human genome, neutrophil serine proteases (NSPs) are thoroughly investigated for their involvement in the onset and progression of inflammatory conditions including respiratory diseases. Uniquely, secreted NSPs not only diffuse within extracellular fluids but also localize to plasma membranes. During neutrophil extracellular trap (NETs) formation, NSPs become an integral part of the secreted chromatin. Such complex behavior renders the understanding of NSPs pathophysiology a challenging task. Here, detailed protocols are shown to visualize, quantify and discriminate free and membrane-bound neutrophil elastase (NE) and cathepsin G (CG) activities in sputum samples. NE and CG are NSPs whose activities have pleiotropic roles in the pathogenesis of cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD): they promote tissue remodeling, regulate downstream immune responses and correlate with lung disease severity. The protocols show how to separate fluid and cellular fraction, as well as the isolation of neutrophils from human sputum for enzymatic activity quantification via small-molecule Förster resonance energy transfer-based (FRET) reporters. To gather specific insights into the relative role of NE and CG activities, a FRET readout can be measured by different technologies: i) in vitro plate reader measurements allow for high-throughput and bulk detection of protease activity; ii) confocal microscopy spatiotemporally resolves membrane-bound activity at the cell surface; iii) small-molecule FRET flow cytometry enables for the rapid evaluation of anti-inflammatory treatments via single-cell protease activity quantification and phenotyping. The implementation of such methods opens the doors to explore NSPs pathobiology and their potential as biomarkers of disease severity for CF and COPD. Given their standardization potential, their robust readout and simplicity of transfer, the described techniques are immediately shareable for implementation across research and diagnostic laboratories.

Relationship between airway dysbiosis, inflammation and lung function in adults with cystic fibrosis

Airway dysbiosis has been associated with lung disease severity in patients with cystic fibrosis (CF). However, the relationship between dysbiosis, airway inflammation and lung function impairement remains poorly understood. The aim of this study was therefore to determine how the structure of the sputum microbiota, airway inflammation markers and spirometry are related in patients with CF. Sputum samples were collected from 106 CF patients between 12 and 72 years. These were analyzed by 16S rRNA gene amplicon sequencing. Moreover, levels of pro-inflammatory cytokines (IL-1β, IL-8, IL-6 and TNF-α) and Neutrophil elastase (NE) were determined. The relationship between the microbiota, inflammation markers and forced expiratory volume in one second percent predicted (FEV₁% predicted) was evaluated by multi-parameter analysis. The microbiota α-diversity correlated inverse with inflammation markers IL-1β, IL-8, TNF-α, NE and positively with FEV₁% predicted. Patients could be divided into 7 clusters based on their microbiota structure. The most diverse cluster was defined by oropharyngeal-like flora (OF) while the others were characterized by the dominance of a single pathogen. Patients with the diverse OF microbiota cluster had lower sputum inflammatory markers and higher FEV₁% predicted compared to patients with a pathogen-dominated microbiota including Pseudomonas aeruginosa. Our results suggest that the diversity of the airway microbiota is an important biomarker of the severity of airway inflammation linking dysbiosis to lung function decline in patients with CF.

Rhinovirus Infection Is Associated With Airway Epithelial Cell Necrosis and Inflammation via Interleukin-1 in Young Children With Cystic Fibrosis

Introduction: The responses of cystic fibrosis (CF) airway epithelial cells (AEC) to rhinovirus (RV) infection are likely to contribute to early pathobiology of lung disease with increased neutrophilic inflammation and lower apoptosis reported. Necrosis of AEC resulting in airway inflammation driven by IL-1 signaling is a characteristic finding in CF detectable in airways of young children. Being the most common early-life infection, RV-induced epithelial necrosis may contribute to early neutrophilic inflammation in CF via IL-1 signaling. As little is known about IL-1 and biology of CF lung disease, this study assessed cellular and pro-inflammatory responses of CF and non-CF AEC following RV infection, with the hypothesis that RV infection drives epithelial necrosis and IL-1 driven inflammation. Methods:Primary AEC obtained from children with (n = 6) and without CF (n = 6) were infected with RV (MOI 3) for 24 h and viable, necrotic and apoptotic events quantified via flow cytometry using a seven-step gating strategy (% total events). IL-1α, IL-1β, IL-1Ra, IL-8, CXCL10, CCL5, IFN-β, IL-28A, IL-28B, and IL-29 were also measured in cell culture supernatants (pg/mL). Results:RV infection reduced viable events in non-CF AEC (p < 0.05), increased necrotic events in non-CF and CF AEC (p < 0.05) and increased apoptotic events in non-CF AEC (p < 0.05). Infection induced IL-1α and IL-1β production in both phenotypes (p < 0.05) but only correlated with necrosis (IL-1α: r = 0.80; IL-1β: r = 0.77; p < 0.0001) in CF AEC. RV infection also increased IL-1Ra in non-CF and CF AEC (p < 0.05), although significantly more in non-CF AEC (p < 0.05). Finally, infection stimulated IL-8 production in non-CF and CF AEC (p < 0.05) and correlated with IL-1α (r = 0.63 & r = 0.74 respectively; p < 0.0001). Conclusions:This study found RV infection drives necrotic cell death in CF AEC. Furthermore, RV induced IL-1 strongly correlated with necrotic cell death in these cells. As IL-1R signaling drives airway neutrophilia and mucin production, these observations suggest RV infection early in life may exacerbate inflammation and mucin accumulation driving early CF lung disease. Since IL-1R can be targeted therapeutically with IL-1Ra, these data suggest a new anti-inflammatory therapeutic approach targeting downstream effects of IL-1R signaling to mitigate viral-induced, muco-inflammatory triggers of early lung disease.

Elastase Exocytosis by Airway Neutrophils Is Associated with Early Lung Damage in Children with Cystic Fibrosis

RATIONALE

Neutrophils are recruited to the airways of individuals with cystic fibrosis (CF). In adolescents and adults with CF, airway neutrophils actively exocytose the primary granule protease elastase (NE), whose extracellular activity correlates with lung damage. During childhood, free extracellular NE activity is measurable only in a subset of patients, and the exocytic function of airway neutrophils is unknown.

OBJECTIVES

To measure NE exocytosis by airway neutrophils in relation to free extracellular NE activity and lung damage in children with CF.

METHODS

We measured lung damage using chest computed tomography coupled with the Perth-Rotterdam Annotated Grid Morphometric Analysis for Cystic Fibrosis scoring system. Concomitantly, we phenotyped blood and BAL fluid leukocytes by flow and image cytometry, and measured free extracellular NE activity using spectrophotometric and Förster resonance energy transfer assays. Children with airway inflammation linked to aerodigestive disorder were enrolled as control subjects.

MEASUREMENTS AND MAIN RESULTS

Children with CF but not disease control children harbored BAL fluid neutrophils with high exocytosis of primary granules, before the detection of bronchiectasis. This measure of NE exocytosis correlated with lung damage (R = 0.55; P = 0.0008), whereas the molecular measure of free extracellular NE activity did not. This discrepancy may be caused by the inhibition of extracellular NE by BAL fluid antiproteases and its binding to leukocytes.

CONCLUSIONS

NE exocytosis by airway neutrophils occurs in all children with CF, and its cellular measure correlates with early lung damage. These findings implicate live airway neutrophils in early CF pathogenesis, which should instruct biomarker development and antiinflammatory therapy in children with CF.

Interleukin-1 is associated with inflammation and structural lung disease in young children with cystic fibrosis

BACKGROUND

Little is known about the role of interleukin (IL)-1 in the pathogenesis of cystic fibrosis (CF) lung disease. This study investigated the relationship between IL-1 signalling, neutrophilic inflammation and structural lung changes in children with CF.

METHODS

Bronchoalveolar lavage fluid (BALf) from 102 children with CF were used to determine IL-1α, IL-1β, IL-8 levels and neutrophil elastase (NE) activity, which were then correlated to structural lung changes observed on chest computed tomography (CT) scans.

RESULTS

IL-1α and IL-1β were detectable in BAL in absence of infection, increased in the presence of bacterial infection and correlated with IL-8 (p < 0.0001), neutrophils (p < 0.0001) and NE activity (p < 0.01 and p < 0.001). IL-1α had the strongest association with structural lung disease (p < 0.01) in the absence of infection (uninfected: p < 0.01 vs. infected: p = 0.122).

CONCLUSION

Our data associates IL-1α with early structural lung damage in CF and suggests this pathway as a novel anti-inflammatory target.

A multicenter evaluation of a proprietary weight loss program for the treatment of marked obesity: a five-year follow-up

OBJECTIVE

The traditional goal of obesity therapy has been the reduction of body weight to an ideal standard. Patient difficulties, however, in reaching this goal have led to a reassessment of weight loss criteria. The Institute of Medicine of the National Academy of Sciences recently proposed that successful long-term weight loss be defined as the reduction of initial weight by 5% or more and the maintenance of this loss for at least 1 year. The present study used these criteria to evaluate the long-term efficacy of a proprietary weight loss program.

METHODS

Patients were 621 persons who had completed a 26-week weight loss program that included 12 weeks of treatment by a very-low-calorie diet. They were recruited from a total of 1,283 eligible persons who had been treated at 36 clinics nationwide. Clinics were randomly selected to participate. Patients' weights were determined in telephone interviews initially conducted 2 years after treatment and then at yearly intervals through 5 years of follow-up.

RESULTS

At the end of treatment, men achieved a mean reduction in initial weight of 25.5 +/- 1% and women 22.6 +/- 1%. Subjects regained substantial amounts of weight by the 2-year follow-up but 77.5% of men and 59.9% of women still maintained losses of 5% or more of body weight. At the 3-year follow-up, 53% of the original sample (of 621 persons) maintained losses of 5% or more and 35% losses of 10% or more. These trends were apparent 4 and 5 years after treatment but the dwindling sample sizes prevented definitive assessments.

DISCUSSION

The findings showed that a program of lifestyle modification combined with the brief use of a very-low-calorie diet was associated with successful weight control in a substantial portion of patients several years after treatment. Long-term weight losses of 5% or more of initial weight are likely to be associated with improvements in health complications.