Impact of Airway Inflammation on the Efficacy of CFTR Modulators

Cystic fibrosis-related chronic rhinosinusitis: the key role of a comprehensive evaluation in the era of highly effective modulator therapy

BACKGROUND

Chronic rhinosinusitis (CRS) is prevalent in cystic fibrosis (CF), significantly affecting quality of life. The introduction of CFTR modulators, including elexacaftor-tezacaftor-ivacaftor (ETI), offers promise for improving sinonasal outcomes.

METHODS

We conducted a retrospective cohort multicenter study analyzing electronic medical records of 45 adult CF patients with CRS, predominantly heterozygous for the ΔF508 mutation, treated with ETI between January 2018 and December 2023. Assessments included Sinonasal Outcome Test 22 (SNOT-22), Nasal Polyp Score (NPS), modified Lund-Kennedy Score (mLKS), Lund-Mackay Score (LMS), and olfactory function using smell loss visual analog scale (VAS) and Sniffin' Sticks identification test (SSIT).

RESULTS

After 12 months of ETI therapy, significant improvements were observed in pulmonary function parameters (FEV1, FVC), CRS severity scores (SNOT-22, NPS, mLKS), radiological findings (LMS), and olfactory function. Subgroup analysis suggested enhanced efficacy in patients with prior endoscopic sinonasal surgery.

CONCLUSIONS

ETI therapy demonstrates comprehensive improvements in CRS and olfactory function in CF patients, highlighting the potential of CFTR modulators in managing sinonasal manifestations.

The effect of triple CFTR modulator therapy and azithromycin on ion channels and inflammation in cystic fibrosis

Background

Inflammation in cystic fibrosis (CF) airways is difficult to treat with well-established regimens often including azithromycin (AZ) as an immunomodulatory drug. As AZ has been reported to require CF transmembrane conductance regulator (CFTR) to be able to reduce interleukin (IL)-8 and given the emergence of highly effective CFTR "triple" modulator therapy (elexacaftor/tezacaftor/ivacaftor; ETI), the aim of this study was to investigate the effect of AZ and ETI, singly and in combination, on ion channel activity and to assess the potential anti-inflammatory effects.

Methods

Electrophysiological assessment of ETI and AZ was performed on three-dimensional cultures of primary CF human bronchial epithelial (HBE) cells using a Multi Trans-Epithelial Current Clamp. IL-8 from NuLi-1 (non-CF) and CuFi-1 (CF) cells treated with AZ was measured by ELISA. Inflammatory mediators from primary CF HBE cells exposed to tumour necrosis factor-α in the presence of AZ, ETI and their combination, were screened using the Proteome Profiler™ Human Cytokine Array Kit, with selected targets validated by ELISA.

Results

AZ did not alter CFTR chloride efflux, nor did it have any synergistic/antagonistic effect in combination with ETI. AZ reduced IL-8 in NuLi-1 but not CuFi-1 cells. The Proteome Profiler™ screen identified several disease-relevant cytokines that were modulated by treatment. Subsequent analysis by ELISA showed IL-8, IL-6, CXCL1 and granulocyte-macrophage colony-stimulating factor to be significantly reduced by treatment with ETI, but not by AZ.

Conclusions

Incorporating ETI into the standard of CF care provides an opportunity to re-evaluate therapeutic regimens to reduce treatment burden and safely discontinue chronic treatments such as AZ, without loss of clinical benefit. Identification of redundant treatments in the era of CFTR modulation may improve medication adherence and overcome potential adverse effects associated with the chronic use AZ and other drugs.

A functional 3D full-thickness model for comprehending the interaction between airway epithelium and connective tissue in cystic fibrosis

Patients with cystic fibrosis (CF) experience severe lung disease, including persistent infections, inflammation, and irreversible fibrotic remodeling of the airways. Although therapy with transmembrane conductance regulator (CFTR) protein modulators reached optimal results in terms of CFTR rescue, lung transplant remains the best line of care for patients in an advanced stage of CF. Indeed, chronic inflammation and tissue remodeling still represent stumbling blocks during treatment, and underlying mechanisms are still unclear. Nowadays, animal models are not able to fully replicate clinical features of the human disease and the conventional in vitro models lack a stromal compartment undergoing fibrotic remodeling. To address this gap, we show the development of a 3D full-thickness model of CF with a human bronchial epithelium differentiated on a connective airway tissue. We demonstrated that the epithelial cells not only underwent mucociliary differentiation but also migrated in the connective tissue and formed gland-like structures. The presence of the connective tissue stimulated the pro-inflammatory behaviour of the epithelium, which activated the fibroblasts embedded into their own extracellular matrix (ECM). By varying the composition of the model with CF epithelial cells and a CF or healthy connective tissue, it was possible to replicate different moments of CF disease, as demonstrated by the differences in the transcriptome of the CF epithelium in the different conditions. The possibility to faithfully represent the crosstalk between epithelial and connective in CF through the full thickness model, along with inflammation and stromal activation, makes the model suitable to better understand mechanisms of disease genesis, progression, and response to therapy.

Epithelial responses to CFTR modulators are improved by inflammatory cytokines and impaired by antiinflammatory drugs

Cystic fibrosis (CF) is a genetic disorder that disrupts CF transmembrane conductance regulator (CFTR) anion channels and impairs airway host defenses. Airway inflammation is ubiquitous in CF, and suppressing it has generally been considered to improve outcomes. However, the role of inflammation in people taking CFTR modulators, small-molecule drugs that restore CFTR function, is not well understood. We previously showed that inflammation enhances the efficacy of CFTR modulators. To further elucidate this relationship, we treated human ΔF508-CF epithelia with TNF-α and IL-17, two inflammatory cytokines that are elevated in CF airways. TNF-α+IL-17 enhanced CFTR modulator-evoked anion secretion through mechanisms that raise intracellular Cl- (Na+/K+/2Cl- cotransport) and HCO3- (carbonic anhydrases and Na+/HCO3- cotransport). This enhancement required p38 MAPK signaling. Importantly, CFTR modulators did not affect CF airway surface liquid viscosity under control conditions but prevented the rise in viscosity in epithelia treated with TNF-α+IL-17. Finally, antiinflammatory drugs limited CFTR modulator responses in TNF-α+IL-17-treated epithelia. These results provide critical insights into mechanisms by which inflammation increases responses to CFTR modulators. They also suggest an equipoise between potential benefits and limitations of suppressing inflammation in people taking modulators, call into question current treatment approaches, and highlight a need for additional studies.

Key inflammatory markers in bronchoalveolar lavage predict bronchiectasis progression in young children with CF

INTRODUCTION

Inflammation appears early in cystic fibrosis (CF) pathogenesis, with specific elevated inflammatory markers in bronchoalveolar lavage fluid (BALF) correlating with structural lung disease. Our aim was to identify markers of airway inflammation able to predict bronchiectasis progression over two years with high sensitivity and specificity.

METHODS

Children with CF with two chest computed tomography (CT) scans and bronchoscopies at a two-year interval were included (n= 10 at 1 and 3 years and n= 27 at 3 and 5 years). Chest CTs were scored for increase in bronchiectasis (Δ%Bx), using the PRAGMA-CF score. BALF collected with the first CT scan were analyzed for neutrophil% (n= 36), myeloperoxidase (MPO) (n= 25), neutrophil elastase (NE) (n= 26), and with a protein array for inflammatory and fibrotic markers (n= 26).

RESULTS

MPO, neutrophil%, and inducible T-cell costimulator ligand (ICOSLG), but not clinical characteristics, correlated significantly with Δ%Bx. Evaluation of neutrophil%, NE, MPO, interleukin-8 (IL-8), ICOSLG, and hepatocyte growth factor (HGF), for predicting an increase of > 0.5% of Δ%Bx in two years, showed that IL-8 had the best sensitivity (82%) and specificity (73%). Neutrophil%, ICOSLG and HGF had sensitivities of 85, 82, and 82% and specificities of 59, 67 and 60%, respectively. The odds ratio for risk of >0.5% Δ%Bx was higher for IL-8 (12.4) than for neutrophil%, ICOSLG, and HGF (5.9, 5.3, and 6.7, respectively). Sensitivity and specificity were lower for NE and MPO).

CONCLUSIONS

High levels of IL-8, neutrophil%, ICOSGL and HGF in BALF may be good predictors for progression of bronchiectasis in young children with CF.

Nanoparticle-based platforms for targeted drug delivery to the pulmonary system as therapeutics to curb cystic fibrosis: A review

Cystic fibrosis (CF) is a genetic disorder of the respiratory system caused by mutation of the Cystic Fibrosis Trans-Membrane Conductance Regulator (CFTR) gene that affects a huge number of people worldwide. It results in difficulty breathing due to a large accumulation of mucus in the respiratory tract, resulting in serious bacterial infections, and subsequent death. Traditional drug-based treatments face hindered penetration at the site of action due to the thick mucus layer. Nanotechnology offers possibilities for developing advanced and effective treatment platforms by focusing on drugs that can penetrate the dense mucus layer, fighting against the underlying bacterial infections, and targeting the genetic cause of the disease. In this review, current nanoparticle-mediated drug delivery platforms for CF, challenges in therapeutics, and future prospects have been highlighted. The effectiveness of the different types of nano-based systems conjugated with various drugs to combat the symptoms and the challenges of treating CF are brought into focus. The toxic effects of these nano-medicines and the various factors that are responsible for their effectiveness are also highlighted.

Cystic fibrosis airway inflammation enables elexacaftor/tezacaftor/ivacaftor-mediated rescue of N1303K CFTR mutation

Rescue of N1303K CFTR by highly effective modulator therapy (HEMT) is enabled by CF airway inflammation. These findings suggest that evaluation of HEMT for rare CFTR mutations must be performed under inflammatory conditions relevant to CF airways. https://bit.ly/3tTcoJE.

Lung Inflammatory Genes in Cystic Fibrosis and Their Relevance to Cystic Fibrosis Transmembrane Conductance Regulator Modulator Therapies

Cystic fibrosis (CF) is a monogenic syndrome determined by over 2000 mutations in the CF Transmembrane Conductance Regulator (CFTR) gene harbored on chromosome 7. In people with CF (PWCF), lung disease is the major determinant of morbidity and mortality and is characterized by a clinical phenotype which differs in the presence of equal mutational assets, indicating that genetic and environmental modifiers play an important role in this variability. Airway inflammation determines the pathophysiology of CF lung disease (CFLD) both at its onset and progression. In this narrative review, we aim to depict the inflammatory process in CF lung, with a particular emphasis on those genetic polymorphisms that could modify the clinical outcome of the respiratory disease in PWCF. The natural history of CF has been changed since the introduction of CFTR modulator therapies in the clinical arena. However, also in this case, there is a patient-to-patient variable response. We provide an overview on inflammatory/immunity gene variants that affect CFLD severity and an appraisal of the effects of CFTR modulator therapies on the inflammatory process in lung disease and how this knowledge may advance the optimization of the management of PWCF.

The future of cystic fibrosis treatment: from disease mechanisms to novel therapeutic approaches

With the 2019 breakthrough in the development of highly effective modulator therapy providing unprecedented clinical benefits for over 90% of patients with cystic fibrosis who are genetically eligible for treatment, this rare disease has become a front runner of transformative molecular therapy. This success is based on fundamental research, which led to the identification of the disease-causing CFTR gene and our subsequent understanding of the disease mechanisms underlying the pathogenesis of cystic fibrosis, working together with a continuously evolving clinical research and drug development pipeline. In this Series paper, we focus on advances since 2018, and remaining knowledge gaps in our understanding of the molecular mechanisms of CFTR dysfunction in the airway epithelium and their links to mucus dysfunction, impaired host defences, airway infection, and chronic inflammation of the lungs of people with cystic fibrosis. We review progress in (and the remaining obstacles to) pharmacological approaches to rescue CFTR function, and novel strategies for improved symptomatic therapies for cystic fibrosis, including how these might be applicable to common lung diseases, such as bronchiectasis and chronic obstructive pulmonary disease. Finally, we discuss the promise of genetic therapies and gene editing approaches to restore CFTR function in the lungs of all patients with cystic fibrosis independent of their CFTR genotype, and the unprecedented opportunities to transform cystic fibrosis from a fatal disease to a treatable and potentially curable one.

Inflammation as a Regulator of the Airway Surface Liquid pH in Cystic Fibrosis

The airway surface liquid (ASL) is a thin sheet of fluid that covers the luminal aspect of the airway epithelium. The ASL is a site of several first-line host defenses, and its composition is a key factor that determines respiratory fitness. Specifically, the acid-base balance of ASL has a major influence on the vital respiratory defense processes of mucociliary clearance and antimicrobial peptide activity against inhaled pathogens. In the inherited disorder cystic fibrosis (CF), loss of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function reduces HCO3- secretion, lowers the pH of ASL (pHASL), and impairs host defenses. These abnormalities initiate a pathologic process whose hallmarks are chronic infection, inflammation, mucus obstruction, and bronchiectasis. Inflammation is particularly relevant as it develops early in CF and persists despite highly effective CFTR modulator therapy. Recent studies show that inflammation may alter HCO3- and H+ secretion across the airway epithelia and thus regulate pHASL. Moreover, inflammation may enhance the restoration of CFTR channel function in CF epithelia exposed to clinically approved modulators. This review focuses on the complex relationships between acid-base secretion, airway inflammation, pHASL regulation, and therapeutic responses to CFTR modulators. These factors have important implications for defining optimal ways of tackling CF airway inflammation in the post-modulator era.

Revisiting Host-Pathogen Interactions in Cystic Fibrosis Lungs in the Era of CFTR Modulators

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators, a new series of therapeutics that correct and potentiate some classes of mutations of the CFTR, have provided a great therapeutic advantage to people with cystic fibrosis (pwCF). The main hindrances of the present CFTR modulators are related to their limitations in reducing chronic lung bacterial infection and inflammation, the main causes of pulmonary tissue damage and progressive respiratory insufficiency, particularly in adults with CF. Here, the most debated issues of the pulmonary bacterial infection and inflammatory processes in pwCF are revisited. Special attention is given to the mechanisms favoring the bacterial infection of pwCF, the progressive adaptation of Pseudomonas aeruginosa and its interplay with Staphylococcus aureus, the cross-talk among bacteria, the bronchial epithelial cells and the phagocytes of the host immune defenses. The most recent findings of the effect of CFTR modulators on bacterial infection and the inflammatory process are also presented to provide critical hints towards the identification of relevant therapeutic targets to overcome the respiratory pathology of pwCF.

Impact of elexacaftor-tezacaftor-ivacaftor on bacterial colonization and inflammatory responses in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a multisystem disease with progressive deterioration. Recently, CF transmembrane conductance regulator (CFTR) modulator therapies were introduced that repair underlying protein defects. Objective of this study was to determine the impact of elexacaftor-tezacaftor-ivacaftor (ETI) on clinical parameters and inflammatory responses in people with CF (pwCF).

METHODS

Lung function (FEV1 ), body mass index (BMI) and microbiologic data were collected at initiation and 3-month intervals for 1 year. Blood was analyzed at baseline and 6 months for cytokines and immune cell populations via flow cytometry and compared to non-CF controls.

RESULTS

Sample size was 48 pwCF, 28 (58.3%) males with a mean age of 28.8 ± 10.7 years. Significant increases in %predicted FEV1 and BMI were observed through 6 months of ETI therapy with no change thereafter. Changes in FEV1 and BMI at 3 months were significantly correlated (r = 57.2, p < 0.01). There were significant reductions in Pseudomonas and Staphylococcus positivity (percent of total samples) in pwCF through 12 months of ETI treatment. Healthy controls (n = 20) had significantly lower levels of circulating neutrophils, interleukin (IL)-6, IL-8, and IL-17A and higher levels of IL-13 compared to pwCF at baseline (n = 48). After 6 months of ETI, pwCF had significant decreases in IL-8, IL-6, and IL-17A levels and normalization of peripheral blood immune cell composition.

CONCLUSIONS

In pwCF, ETI significantly improved clinical outcomes, reduced systemic pro-inflammatory cytokines, and restored circulating immune cell composition after 6 months of therapy.

Prevalence and Determinants of Wheezing and Bronchodilatation in Children With Cystic Fibrosis: A Retrospective Cohort Study

Background

Many patients with cystic fibrosis (CF) wheeze, and are dubbed as having CF-asthma. Understanding the determinants of such wheezing may avoid unnecessary treatments and open newer treatment avenues.

Objectives

Main: To evaluate the prevalence and characteristics of wheezing and a positive bronchodilatory response (BDR) in children with CF. Secondary: To identify the predictive markers and the impact of current wheezing a positive BDR.

Methods

A retrospective single-center study in children with CF. We determined the characteristics of physician-reported wheeze in patients <6 years, and a BDR in patients aged 6-17 years. Anthropometric, lung function, laboratory, genetic and microbiological data were recorded in all groups. Variables were compared using the Chi2 and Student t-tests, and ANOVA.

Results

125 preschool and 69 school-aged children and adolescents with CF were included in the study. 71.2% of patients <6 years of age had had at least one episode of wheezing: 26.3% of patients were Transient Early Wheezers, 12.6% Late Onset Wheezers and 37.9% were Persistent Wheezers. The prevalence of a positive BDR was 73.5, 48.5, and 52.9% in the 6-8 years, 10-12 years, and 15-17 years age groups, respectively. Allergic factors were not predictive of wheezing in preschoolers. In the 6-8 years age group, the sum of wheal diameters of allergic skin prick tests (SPT, house dust mite + cat + dog dander) was greater in those with a BDR vs. no BDR (4 [2.0-8.8] vs. 1 [0-7.0] mm, p = 0.01). The presence of Pseudomonas aeruginosa in the bronchial secretions before 3 years of age was not significantly associated with either the presence of wheezing at the age of 6 years or a BDR in school-aged children and adolescents. The proportion of homozygous p.F508del patients was significantly lower in the group of patients who had wheezed by 6 years of age (60% vs. 72.7%, p = 0.009), but higher in the 6-8 years old group with a BDR vs. no BDR (64% vs. 36%, p = 0.04). Current wheezers at 6 years had a lower mean FEV1 vs. the non-current wheezers (91.5 ± 4.4% vs. 100.9 ± 2.4%; p = 0.047). Similarly, forced vital capacity (FVC) was significantly lower in the 6-8 years old group with BDR vs. no BDR (85 ± 19 vs. 101 ± 21%, p = 0.015).

Conclusion

Wheezing and BDR are very frequent findings in children with CF. Current wheeze at the age of 6 years was associated with worse lung function. Labeling wheezing in CF as "CF-Asthma" is misleading since the determinants are different, and may lead to inappropriate prescriptions of inhaled steroids.