ROCK STUDY in CF: sustained anti-inflammatory effects of lumacaftor-ivacaftor in sputum and peripheral blood samples of adult patients with cystic fibrosis-an observational study

Innate Immunity in Cystic Fibrosis: Varied Effects of CFTR Modulator Therapy on Cell-to-Cell Communication

Cystic Fibrosis (CF) is a life-shortening, multi-organ disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Prominent clinical features of CF take place in the lung, hallmarked by cycles of bacterial infection and a dysfunctional inflammatory airway response, leading to eventual respiratory failure. Bidirectional crosstalk between epithelial cells, leukocytes (e.g., neutrophils, macrophages) and bacteria via release of intra-cellular mediators is key to driving inflammation in CF airways. In recent years, a highly effective combination of therapeutics targeting the CFTR defect have revolutionized treatment in CF. Despite these advancements and due to the complexity of the immune response in the CF airway, the full impact of highly effective modulator therapy (HEMT) on airway inflammation is not fully determined. This review provides the evidence to date on crosstalk mechanisms between host epithelium, leukocytes and bacteria and examines the effect of HEMT on both soluble and membrane-derived immune mediators in clinical samples. The varied effects of HEMT on expression of key proteases, cytokines and extracellular vesicles (EVs) in relation to clinical parameters is assessed. Advances in treatment with HEMT have shown potential in dampening the chronic inflammatory response in CF airways. However, to fully quell inflammation and maximize lung tissue resilience, further interventions may be necessary. Exploring the effects of HEMT on key immune mediators paves the way for identifying new anti-inflammatory approaches targeting host immune cell interactions, such as EV-directed lung therapies.

Mucus Structure, Viscoelastic Properties, and Composition in Chronic Respiratory Diseases

The respiratory mucus, a viscoelastic gel, effectuates a primary line of the airway defense when operated by the mucociliary clearance. In chronic respiratory diseases (CRDs), such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF), the mucus is overproduced and its solid content augments, changing its structure and viscoelastic properties and determining a derangement of essential defense mechanisms against opportunistic microbial (virus and bacteria) pathogens. This ensues in damaging of the airways, leading to a vicious cycle of obstruction and infection responsible for the harsh clinical evolution of these CRDs. Here, we review the essential features of normal and pathological mucus (i.e., sputum in CF, COPD, and asthma), i.e., mucin content, structure (mesh size), micro/macro-rheology, pH, and osmotic pressure, ending with the awareness that sputum biomarkers (mucins, inflammatory proteins and peptides, and metabolites) might serve to indicate acute exacerbation and response to therapies. There are some indications that old and novel treatments may change the structure, viscoelastic properties, and biomarker content of sputum; however, a wealth of work is still needed to embrace these measures as correlates of disease severity in association with (or even as substitutes of) pulmonary functional tests.

Laboratory Tools to Predict CFTR Modulator Therapy Effectiveness and to Monitor Disease Severity in Cystic Fibrosis

The implementation of cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator drugs into clinical practice has been attaining remarkable therapeutic outcomes for CF, a life-threatening autosomal recessive genetic disease. However, there is elevated CFTR allelic heterogeneity, and various individuals carrying (ultra)rare CF genotypes remain without any approved modulator therapy. Novel translational model systems based on individuals' own cells/tissue are now available and can be used to interrogate in vitro CFTR modulator responses and establish correlations of these assessments with clinical features, aiming to provide prediction of therapeutic effectiveness. Furthermore, because CF is a progressive disease, assessment of biomarkers in routine care is fundamental in monitoring treatment effectiveness and disease severity. In the first part of this review, we aimed to focus on the utility of individual-derived in vitro models (such as bronchial/nasal epithelial cells and airway/intestinal organoids) to identify potential responders and expand personalized CF care. Thereafter, we discussed the usage of CF inflammatory biomarkers derived from blood, bronchoalveolar lavage fluid, and sputum to routinely monitor treatment effectiveness and disease progression. Finally, we summarized the progress in investigating extracellular vesicles as a robust and reliable source of biomarkers and the identification of microRNAs related to CFTR regulation and CF inflammation as novel biomarkers, which may provide valuable information for disease prognosis.