Bronchoalveolar lavage and tracheal aspirate for assessing airway inflammation in children

Acetylcholine, Fatty Acids, and Lipid Mediators Are Linked to COVID-19 Severity

Lipid and cholinergic mediators are inflammatory regulators, but their role in the immunopathology of COVID-19 is still unclear. Here, we used human blood and tracheal aspirate (TA) to investigate whether acetylcholine (Ach), fatty acids (FAs), and their derived lipid mediators (LMs) are associated with COVID-19 severity. First, we analyzed the perturbation profile induced by SARS-CoV-2 infection in the transcriptional profile of genes related to the ACh and FA/LM pathways. Blood and TA were used for metabolomic and lipidomic analyses and for quantification of leukocytes, cytokines, and ACh. Differential expression and coexpression gene network data revealed a unique transcriptional profile associated with ACh and FA/LM production, release, and cellular signaling. Transcriptomic data were corroborated by laboratory findings: SARS-CoV-2 infection increased plasma and TA levels of arachidonic acid, 5-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid, 11-hydroxy-5Z,8Z,12E,14Z-eicosatetraenoic acid, and ACh. TA samples also exhibited high levels of PGE₂, thromboxane B₂, 12-oxo-5Z,8Z,10E,14Z-eicosatetraenoic acid, and 6-trans-leukotriene B₄ Bioinformatics and experimental approaches demonstrated robust correlation between transcriptional profile in Ach and FA/LM pathways and parameters of severe COVID-19. As expected, the increased neutrophil-to-lymphocyte ratio, neutrophil counts, and cytokine levels (IL-6, IL-10, IL-1β, and IL-8) correlated with worse clinical scores. Glucocorticoids protected severe and critical patients and correlated with reduced Ach levels in plasma and TA samples. We demonstrated that pulmonary and systemic hyperinflammation in severe COVID-19 are associated with high levels of Ach and FA/LM. Glucocorticoids favored the survival of patients with severe/critical disease, and this effect was associated with a reduction in ACh levels.

Matrix Metalloproteinases on Severe COVID-19 Lung Disease Pathogenesis: Cooperative Actions of MMP-8/MMP-2 Axis on Immune Response through HLA-G Shedding and Oxidative Stress

Patients with COVID-19 predominantly have a respiratory tract infection and acute lung failure is the most severe complication. While the molecular basis of SARS-CoV-2 immunopathology is still unknown, it is well established that lung infection is associated with hyper-inflammation and tissue damage. Matrix metalloproteinases (MMPs) contribute to tissue destruction in many pathological situations, and the activity of MMPs in the lung leads to the release of bioactive mediators with inflammatory properties. We sought to characterize a scenario in which MMPs could influence the lung pathogenesis of COVID-19. Although we observed high diversity of MMPs in lung tissue from COVID-19 patients by proteomics, we specified the expression and enzyme activity of MMP-2 in tracheal-aspirate fluid (TAF) samples from intubated COVID-19 and non-COVID-19 patients. Moreover, the expression of MMP-8 was positively correlated with MMP-2 levels and possible shedding of the immunosuppression mediator sHLA-G and sTREM-1. Together, overexpression of the MMP-2/MMP-8 axis, in addition to neutrophil infiltration and products, such as reactive oxygen species (ROS), increased lipid peroxidation that could promote intensive destruction of lung tissue in severe COVID-19. Thus, the inhibition of MMPs can be a novel target and promising treatment strategy in severe COVID-19.

Heat Shock Protein-70 Levels Are Associated With a State of Oxidative Damage in the Development of Bronchopulmonary Dysplasia

Background: Heat shock protein-70 (Hsp-70) exhibits cytoprotective effects against oxidative stress-induced airway injury. This study aimed to examine Hsp-70 and 8-hydroxy-2'-deoxyguanosine (8-OHdG) from tracheal aspirates (TA) in very low-birth weight (VLBW) preterm infants to predict the development of bronchopulmonary dysplasia (BPD). Methods: This birth cohort study enrolled 109 VLBW preterm infants, including 32 infants who developed BPD. Hsp-70 and 8-OHdG concentrations from TA were measured by immunoassay. The apoptosis of TA epithelial cells obtained on Day 28 after birth was measured using annexin-V staining assay. Results: Hsp-70 and 8-OHdG levels in TA fluid were persistently increased from Day 1 to Day 28 of life in the BPD group. Multiple linear regression analysis demonstrated that BPD was significantly associated with gestational age, respiratory distress syndrome, and TA Hsp-70 and 8-OHdG levels on post-natal Day 28. The TA Hsp-70 level positively correlated with TA 8-OHdG level on the Day 1 (r = 0.47) and Day 28 of life (r = 0.68). Incubation of recombinant Hsp-70 with primary epithelial cells derived from TA of patients decreased hydrogen peroxide-induced epithelial cell death. Conclusions: Hsp-70 levels are associated with a state of oxidative injury in the development of BPD.

Detection of EGFR Mutations Using Bronchial Washing-Derived Extracellular Vesicles in Patients with Non-Small-Cell Lung Carcinoma

Simple Summary

Considering the spatiotemporal heterogeneity, more frequent monitoring of the disease progress using less-invasive liquid biopsy technologies is highly desired. Here, we demonstrate that epidermal growth factor receptor (EGFR) mutations could be readily detected from minimally invasive bronchial washing (BW)-derived EVs with good accuracy. The acquisition of T790M resistance mutation was detected earlier in BW-derived EVs than in plasma or tissue samples. The longitudinal analysis of BW-derived EVs showed excellent correlation with the disease progression measured by CT images. We demonstrate the clinical potential of BW-derived EVs as a liquid-biopsy sample for prognosis and precision medicine in patients with lung cancer.

Abstract

The detection of epidermal growth factor receptor (EGFR) mutation, based on tissue biopsy samples, provides a valuable guideline for the prognosis and precision medicine in patients with lung cancer. In this study, we aimed to examine minimally invasive bronchial washing (BW)-derived extracellular vesicles (EVs) for EGFR mutation analysis in patients with lung cancer. A lab-on-a-disc equipped with a filter with 20-nm pore diameter, Exo-Disc, was used to enrich EVs in BW samples. The overall detection sensitivity of EGFR mutations in 55 BW-derived samples was 89.7% and 31.0% for EV-derived DNA (EV-DNA) and EV-excluded cell free-DNA (EV-X-cfDNA), respectively, with 100% specificity. The detection rate of T790M in 13 matched samples was 61.5%, 10.0%, and 30.8% from BW-derived EV-DNA, plasma-derived cfDNA, and tissue samples, respectively. The acquisition of T790M resistance mutation was detected earlier in BW-derived EVs than plasma or tissue samples. The longitudinal analysis of BW-derived EVs showed excellent correlation with the disease progression measured by CT images. The EGFR mutations can be readily detected in BW-derived EVs, which demonstrates their clinical potential as a liquid-biopsy sample that may aid precise management, including assessment of the treatment response and drug resistance in patients with lung cancer.

Correlates of Elevated Interleukin-6 and 8-Hydroxy-2'-Deoxyguanosine Levels in Tracheal Aspirates from Very Low Birth Weight Infants Who Develop Bronchopulmonary Dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains the most common complication of very low birth weight (VLBW) preterm infants, and inflammatory regulation plays a role in the development of the BPD. Interleukin-6 (IL-6) has an important role in airway inflammation and therefore can be used as a marker of airway injury. The study aimed to compare the changes between IL-6 and oxidative stress marker with 8-hydroxy-2'-deoxyguanosine (8-OHdG) from serum and tracheal aspiration (TA) in VLBW preterm infants following development of BPD.

METHODS

This birth cohort study enrolled 80 VLBW preterm infants, including 26 who developed BPD. All infants completed the study and survived at 36 weeks postmenstrual age. IL-6 and 8-OHdG concentrations from serum and TA on Day 1 and Day 28 after birth were measured using immunoassay.

RESULTS

IL-6 and 8-OHdG in serum and TA were higher in the BPD group than in the non-BPD group on the 1^st day after birth (p < 0.05). The IL-6 and 8-OHdG levels in TA fluid were persistently increased on the 28^th day of life in the BPD group (p < 0.05). The TA IL-6 was positively correlated with 8-OHdG levels on the 1^st day (r = 0.64, p < 0.05) and 28^th day of life (r = 0.76, p < 0.05). Based on receiver operating characteristic curves as a predictor of BPD development, TA IL-6 (cutoff, 456.8 pg/mg) had 81.5% sensitivity and 77.8% specificity, whereas TA 8-OHdG (cutoff, 4.4 ng/mg) had a sensitivity of 81.5% and a specificity of 64.4%.

CONCLUSION

Persistent inflammation with oxidative DNA damage in the respiratory tract may be a crucial mechanism in BPD.

Site of Bronchoalveolar Lavage Via Flexible Bronchoscopy and Fluid Return in Children

BACKGROUND

Despite its widespread use as a diagnostic tool, the procedure for bronchoalveolar lavage (BAL) via flexible bronchoscopy is not standardized in children. Our objective was to examine the dissimilarities in fluid return between the different lobes in children undergoing flexible bronchoscopies with BAL.

METHODS

We conducted a review of all pediatric flexible bronchoscopies with BAL conducted at a single institution over a 2-year period. Our predictor of interest was the site of the BAL. Our outcome of interest was the percent of fluid return. We used 1-way analysis of variance with subsequent pairwise comparisons for unadjusted analyses and multivariable linear regression for adjusted analyses.

RESULTS

We identified 529 procedures that met prespecified criteria. The mean (SD) percent of fluid return was 52.1 (14.4) for the right middle lobe, 50.7 (16.0) for the lingula (LIN), 50.5 (18.6) for the right or left upper lobes other than LIN (R/L-UL), and 42.2 (18.7) for the right or left lower lobes (R/L-LL). The R/L-LL had significantly lower fluid return when compared with each of the other lobes (P<0.05 for all pairwise comparisons); in contrast, there was no significant difference in fluid return between the other lobes. In our main analysis adjusting for potential confounders, performing the BAL in the right middle lobe, LIN, or R/L-UL increased the fluid return by 11.1% [95% confidence interval (CI), 6.2-16.1], 9.5% (95% CI, 3.2-15.8), and 8.7% (95% CI, 0.9-16.5%), respectively, when compared with the R/L-LL.

CONCLUSION

Our results suggest that the lower lobes provide the lowest BAL fluid return in children, whereas the other lobes seem to perform similarly.

Comparison of two aspiration techniques of bronchoalveolar lavage in children

BACKGROUND

Although bronchoalveolar lavage (BAL) via flexible bronchoscopy is an essential diagnostic tool, its technique is not standardized in children. Our objective was to compare two different aspiration techniques of BAL in children (continuous wall suction vs. handheld syringe suction) in regards to the percentage of fluid recovered and the odds of performing a technically acceptable procedure (i.e., >40% of volume return).

METHODS

We conducted a review of all pediatric flexible bronchoscopies with BAL conducted at our institution over a 2-year period. To minimize the differences between groups at baseline and reduce the possibility of bias, we used one-to-one propensity score (PS) caliper matching with no replacement for statistical analyses.

RESULTS

We identified 539 procedures that met pre-specified criteria. There were considerable covariate imbalances between procedures in the handheld syringe group (n = 147) and those in the continuous wall group (n = 392); however, these imbalances were substantially reduced after the PS matching. In the matched sample (n = 236), children in the handheld syringe group had ∼7% higher volume return (95% CI = 3.4-11.0, P < 0.001) from BAL and threefold higher odds (95% CI = 1.5-8.6, P = 0.002) of performing a technically acceptable procedure.

CONCLUSIONS

Our results suggest that handheld syringe suction offers a higher percentage of volume return from BAL and increases the odds of performing a technically acceptable procedure in children when compared to continuous wall suction.

Comparison of DNA extraction methods for microbial community profiling with an application to pediatric bronchoalveolar lavage samples

Barcoded amplicon sequencing is rapidly becoming a standard method for profiling microbial communities, including the human respiratory microbiome. While this approach has less bias than standard cultivation, several steps can introduce variation including the type of DNA extraction method used. Here we assessed five different extraction methods on pediatric bronchoalveolar lavage (BAL) samples and a mock community comprised of nine bacterial genera to determine method reproducibility and detection limits for these typically low complexity communities. Additionally, using the mock community, we were able to evaluate contamination and select a relative abundance cut-off threshold based on the geometric distribution that optimizes the trade off between detecting bona fide operational taxonomic units and filtering out spurious ones. Using this threshold, the majority of genera in the mock community were predictably detected by all extraction methods including the hard-to-lyse Gram-positive genus Staphylococcus. Differences between extraction methods were significantly greater than between technical replicates for both the mock community and BAL samples emphasizing the importance of using a standardized methodology for microbiome studies. However, regardless of method used, individual patients retained unique diagnostic profiles. Furthermore, despite being stored as raw frozen samples for over five years, community profiles from BAL samples were consistent with historical culturing results. The culture-independent profiling of these samples also identified a number of anaerobic genera that are gaining acceptance as being part of the respiratory microbiome. This study should help guide researchers to formulate sampling, extraction and analysis strategies for respiratory and other human microbiome samples.

A simple method of reducing complications of pediatric nonbronchoscopic bronchoalveolar lavage

Our objective was to determine whether a simple method of maintaining positive pressure ventilation during nonbronchoscopic bronchoalveolar lavage (NB-BAL) would successfully reduce the incidence and/or severity of desaturation events. Our design was a clinical trial with historical controls. Seventy ventilated pediatric patients undergoing diagnostic NB-BAL participated. Two NB-BAL techniques were compared: 1) the "unsealed" method, where the suction catheter was passed through an open system, maintaining oxygenation but not airway pressure; and 2) the "sealed" technique, which was identical except that the catheter was passed through a diaphragm, maintaining positive pressure ventilation throughout. NB-BAL was performed on 35 patients using the "unsealed" technique and 2 years later on 35 patients using the "sealed" method. Heart rate and oxyhemoglobin saturation (SaO(2)) were recorded before, during, and after NB-BAL. There was no difference between groups with regard to demographic data, oxygenation, or ventilatory requirements (P >or= 0.1). The "sealed" group experienced a median drop in SaO(2) of 6.0% (range, -6% to 44%), and the "unsealed" group a drop of 13.0% (-2% to 61%), during NB-BAL (P < 0.05). Patients with oxygenation index greater than 10 experienced the most severe desaturation events in both groups: 53.8% of patients in the "sealed" group with oxygenation index >10 desaturated to <80% vs. 91.6% in the "unsealed" group (P < 0.05). In conclusion, we describe a simple, inexpensive modification of the NB-BAL technique that reduces the incidence and severity of desaturation during NB-BAL.

Eosinophil granule proteins in the assessment of airway inflammation in pediatric bronchial asthma

Eosinophil granule proteins such as eosinophil cationic protein (ECP), eosinophil peroxidase (EPO) and eosinophil protein X (EPX) in serum and urine are indirect measures of eosinophil activity. The measures have been evaluated for prediction, diagnosis and monitoring of anti-inflammatory treatment modalities in children with asthma. Assessments in serum and urine are highly dependent on sampling procedures and must be performed under strictly controlled conditions using standardized sampling and laboratory procedures. The measures are influenced by circadian and seasonal variations. Measurement of the eosinophil granule proteins does not improve the predictive value of a family history of atopy. Due to insufficient sensitivity and specificity, the measures are not useful in the diagnosis of asthma in children, and the clinical use of eosinophil proteins in the individual child for assessment of asthma severity has not been sufficiently validated. Serum and urine eosinophil granule proteins, however, may be useful in extending our knowledge of suppressive effects on eosinophil activity of various doses, devices and administration regimens of inhaled glucocorticoids in children. Such evaluations may be performed in randomized, double-blind trials of well-defined age groups and they should include measures of compliance. One important aspect to look at would be the distinction between suppressive effects on eosinophil activity and clinically important anti-inflammatory effects. Considering the complexity of airway inflammation and the heterogeneity of childhood asthma, however, it may be too simplistic to look for a single measure of the inflammatory processes. In the future, perhaps, a combination of products of inflammatory cells may give more clinically relevant information with respect to prediction, diagnosis, monitoring and outcome of childhood asthma.

Invasive monitoring of airway inflammation

What we know: Ethical concerns have limited research involving invasive bronchoscopy techniques in young children. No longitudinal studies have been conducted to compare the findings of bronchial biopsy or bronchoalveolar lavage in young children with transient episodic wheeze versus asthma. Children with atopic asthma have more airway eosinophils and mast cells than children with viral-associated wheeze. Both neutrophilic and eosinophilic patterns of inflammation are present in asthma. What we need to know: Can we establish robust normal values for tissue and fluid samples obtained at bronchoscopy or bronchoalveolar lavage? Do biopsy specimens taken at the carina tell us about the pathological processes occurring in asthma? Can we use invasive procedures to predict which children with wheeze will continue to wheeze and develop a classical asthma phenotype? Can we use invasive procedures to guide asthma therapy? Can we expect airway inflammation to resolve with anti-inflammatory medication? Can we correlate invasive with non-invasive measures of inflammation? Can we use our understanding of pro- and anti-inflammatory pathways to develop new therapeutic interventions? Is there a presymptomatic phase of inflammation?

Bronchoscopy--how and when?

At the Royal Brompton Hospital, we perform over 200 flexible bronchoscopies per year in children. We will be presenting a series of five articles describing various aspects of our clinical and research practice. This first article is about the basics of how and when to perform flexible bronchoscopy. It highlights aspects of training, preparation of the patient and the equipment required. It discusses anaesthesia and gives practical details on how to actually use the bronchoscope, as well as detailing techniques of lavage, brushings and biopsy. Particular attention is paid to indications and contraindications, as well as potential complications.

"CF asthma": what is it and what do we do about it?

The diagnosis of "CF asthma" is problematic and it is difficult to determine which patients have a combination of CF and asthma and which have asthma like symptoms caused by inflammation of the CF lung. This may not matter, however; the relevance lies in the possible approaches to treatment.

Inflammation, infection, and pulmonary function in infants and young children with cystic fibrosis

Our aim was to study the effect of lower airway infection on clinical parameters, pulmonary function tests, and inflammation in clinically stable infants and young children with cystic fibrosis (CF). To accomplish this goal, a prospective cohort of screened CF patients under 4 years of age were studied, using elective anesthesia and intubation for: passive respiratory mechanics (single breath occlusion passive deflation) and lung volumes (nitrogen washout), under neuromuscular blockade; and bronchoalveolar lavage (BAL) of 3 main bronchi for cytology, cytokine interleukin (IL)-8, and quantitative microbiology. There were 22 children studied, with a mean age of 23.2 months (6.7-44 months). A greater relative risk of lower airway pathogens was associated with prior respiratory admission (3.60, 95% confidence interval [CI] 2.87-4.51), history of asthma (1.75, 95% CI 1.52-2.03), and chronic symptoms (1.50, 95% CI 1.23-1.83), especially wheeze (1.88, 95% CI 1.61-2.19). Lower respiratory pathogens (> or = 10 cfu/ml BAL) were found in 14 out of 22, and greater than 10(5) cfu/ml in 8 out of 22 subjects. The level of pathogens in BAL (log10 cfu/ml) explained 78% of the variability in percent neutrophils and 34% of the variability in IL-8 levels. Pathogen level also correlated with pulmonary function tests of specific respiratory system compliance (r -0.49, p = 0.02) and functional residual capacity over total lung capacity (r 0.49, p = 0.03). We conclude that the presence of pathogens in the lower airways correlated with levels of inflammation, respiratory system compliance, and degree of air trapping.