Comparison of inhaled mannitol/dornase alfa combination and daily dornase alfa alone in children with cystic fibrosis

Neutrophil extracellular traps promote proliferation of pulmonary smooth muscle cells mediated by CCDC25 in pulmonary arterial hypertension

BACKGROUND

Previous studies have indicated that neutrophil extracellular traps (NETs) play a pivotal role in pathogenesis of pulmonary arterial hypertension (PAH). However, the specific mechanism underlying the impact of NETs on pulmonary artery smooth muscle cells (PASMCs) has not been determined. The objective of this study was to elucidate underlying mechanisms through which NETs contribute to progression of PAH.

METHODS

Bioinformatics analysis was employed in this study to screen for potential molecules and mechanisms associated with occurrence and development of PAH. These findings were subsequently validated in human samples, coiled-coil domain containing 25 (CCDC25) knockdown PASMCs, as well as monocrotaline-induced PAH rat model.

RESULTS

NETs promoted proliferation of PASMCs, thereby facilitating pathogenesis of PAH. This phenomenon was mediated by the activation of transmembrane receptor CCDC25 on PASMCs, which subsequently activated ILK/β-parvin/RAC1 pathway. Consequently, cytoskeletal remodeling and phenotypic transformation occur in PASMCs. Furthermore, the level of NETs could serve as an indicator of PAH severity and as potential therapeutic target for alleviating PAH.

CONCLUSION

This study elucidated the involvement of NETs in pathogenesis of PAH through their influence on the function of PASMCs, thereby highlighting their potential as promising targets for the evaluation and treatment of PAH.

Cystic fibrosis year in review 2022

Remarkable medical advancements have been made for people with cystic fibrosis (CF) in recent years, with an abundance of research continuing to be conducted worldwide. With concern for limitations in access to highly effective CFTR modulators, as well as the recent Coronavirus Disease-19 pandemic, there has been a consistent effort to understand and improve CF screening, disease burden, diagnosis, and management. Our aim in this review is to present articles from 2022 with an emphasis on clinically relevant studies. We hope this will serve as a broad overview of the research published in the past year.

Physiology and pathophysiology of human airway mucus

The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas-liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), non-CF bronchiectasis (NCFB), and primary ciliary dyskinesia (PCD). A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.

Dornase alfa in Cystic Fibrosis: indications, comparative studies and effects on lung clearance index

Cystic fibrosis (CF) is the most common inherited disease in Caucasian populations, affecting around 50,000 patients in Europe and 30,000 in United States. A mutation in CF trans-membrane conductance regulator (CFTR) gene changes a protein (a regulated chloride channel), which is expressed in many tissues. Defective CFTR results in reduced chloride secretion and an overage absorption of sodium across the epithelia, leading to thickened secretions in organs such as pancreas and lung. Gradually, there have been considerable improvements in the survival of people with CF, thanks to substantial changes in specialized CF care and the discovery of new CFTR modulators drugs. Nevertheless, lung disease remains the most common cause of death. For these reasons improvement of sputum clearance is a major therapeutic aim in CF. So far, symptomatic mucolytic therapy is mainly based on inhalation of dornase alfa, hypertonic saline or mannitol, in combination with physiotherapy. The major component of mucus in CF is pus including viscous material such as polymerized DNA derived from degraded neutrophils. Dornase alfa cleaves the DNA released from the neutrophils and reduces mucous viscosity, and further prevent airway infections and damage to the lung parenchyma. In this review we will summarize the current knowledge on dornase alfa in the treatment of CF lung disease, especially highlighting the positive effect on lung clearance index, a sensitive measure of ventilation inhomogeneity.

The effect of Pseudomonas aeruginosa eradication regimens on chronic colonization and clinical outcomes in pediatric patients with cystic fibrosis

BACKGROUND

Chronic Pseudomonas aeruginosa colonization (Pa-CC) affects cystic fibrosis (CF) progression, including pulmonary exacerbations and pulmonary function tests. There are few studies of the effects of eradication protocols on colonization time. Here, we aimed to evaluate the effect of eradication regimens on chronic colonization and assess the impact of Pa-CC on body mass index, lung functions, and pulmonary exacerbations.

METHODS

A retrospective review was conducted of medical records, over a period of 11 years, of children aged under 18 years with CF who had Pa-CC in our tertiary care pediatric hospital.

RESULTS

Pseudomonas aeruginosa was detected in 215 of our patients with CF during the study period. Forty-four patients with Pa-CC were recruited for the study. The eradication treatment for the initial acquisition of P. aeruginosa was inhaled antibiotics in 27 (61.4%) patients; the remainder were given intravenous antibiotics. It was observed that eradication treatment with either IV or inhaled antibiotics did not affect the time between the P. aeruginosa and the time of Pa-CC(P = 0.791). There was a non-significant decrease in the body mass index z-score from the Pa-IA to the last visit(P = 0.27), a significant decline in forced expiratory volume in 1 s (FEV1%) (P = 0.01) over time, and the annual number of exacerbations after colonization was significantly higher than before colonization (P = 0.03).

CONCLUSIONS

There was no difference between eradication regimens in delaying the age at Pa-CC. Pseudomonas aeruginosa colonization in patients with CF was also associated with poorer lung functions, lower body mass index, and more pulmonary exacerbation regardless of mucoid type. Consequently, to slow the progression of lung disease, we must prevent Pa-CC, which we can achieve with early eradication. Despite conventional eradication protocols, future studies need to evaluate those who fail to clear P. aeruginosa.