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

The impact of cystic fibrosis transmembrane conductance regulator (CFTR) modulators on the pulmonary microbiota

Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy has significantly changed the course of the disease in people with cystic fibrosis (CF) (pwCF). The approved triple therapy of elexacaftor, tezacaftor and ivacaftor (ETI), commercially known as Trikafta, increases CFTR channel function, leading to improvements in sweat chloride concentration, exercise capacity, body mass index, lung function and chronic respiratory symptoms. Because of this, the majority of pwCF are living longer and having fewer CF exacerbations. However, colonization with the common CF respiratory pathogens persists and remains a major cause of morbidity and mortality. Here, we review the current literature on the effect of ETI on the respiratory microbiota and discuss the challenges in addressing CF lung infections in the era of these new life-extending therapies.

The Role of Triple CFTR Modulator Therapy in Reducing Systemic Inflammation in Cystic Fibrosis

PURPOSE

Cystic fibrosis (CF) is a genetic disease caused by mutations in the CFTR gene, leading to multisystemic complications, particularly in the lungs. CFTR dysfunction results in altered ion transport, chronic inflammation, and progressive lung damage. The triple therapy elexacaftor/tezacaftor/ivacaftor (ETI) has demonstrated significant improvements in pulmonary function and quality of life. This study aimed to evaluate the anti-inflammatory effects of ETI by analysing systemic cytokine profiles over 12 months.

METHODS

A prospective study included 32 CF patients ≥ 18 years with at least one delF508 mutation, undergoing ETI therapy. Clinical stability was ensured prior to therapy initiation. Demographic data, BMI (Body Mass Index), FEV1% (Forced expiratory Volume in the first second), VR/TLC (residual volume/total lung capacity) and sweat chloride concentrations were recorded at baseline, 6 months and 12 months. Inflammatory markers, including fibrinogen, C-reactive protein (CRP), and a panel of 8 cytokines, were measured using multiplex bead-based immunoassays and electrochemiluminescence. Longitudinal changes were analysed using mixed-effects models and statistical tests, with significance set at p < 0.05.

RESULTS

During a 12-month follow-up, the neutrophils number and proinflammatory biomarkers analyzed, fibrinogen, CRP, GM-CSF, IFN- γ, IL-1 α, IL-1 β, IL-8 (CXCL8), IL-12p70, IL-17A (CTLA-8), and TNF-α, significantly decreased, while eosinophils remained stable. Mixed-effects models confirmed the significant association of inflammatory biomarkers with FEV1, BMI, sweat chloride levels, and VR/TLC highlighting the role of inflammation in the progression of CF.

CONCLUSIONS

ETI demonstrated marked anti-inflammatory effects in CF patients, reducing systemic inflammation and improving clinical parameters.

Real-life impact of genotype and severity of lung disease on efficacy of elexacaftor-tezacaftor-ivacaftor in people with cystic fibrosis

BACKGROUND

Elexacaftor-tezacaftor-ivacaftor (ETI) therapy has shown improvement in lung function, BMI and reduction in pulmonary exacerbations but the impact of genotype and severity of lung disease on heterogeneity of ETI efficacy in real life is not known.

METHODS

This is a prospective observational study. Clinical data at baseline and at one-year of therapy were compared for the total cohort and for two subgroups; genotype [homozygous vs. heterozygous for F508del], and severity of lung disease at ETI initiation (ppFEV1 <80 % vs. ≥80 %).

RESULTS

Among the total cohort of 115 pwCF, median age of 23 (17, 32) years, 66 (58 %) were homozygous, 76 (66 %) had ppFEV1 <80 %. Significant increases in mean ppFEV1 and mean BMI and decrease in MRSA and Pa culture positivity on sputum/throat swab were observed at one year of ETI therapy in the total cohort, and in groups based on either genotype or disease severity (p < 0.05 in all). Comparing one-year prior to one-year on ETI therapy, significant improvements were noted in pulmonary exacerbations, hospital admissions, antibiotic courses, number of pwCF receiving daily chest therapy, dornase alfa and hypertonic saline in the total cohort and in all four subgroups (p < 0.05 for all). Though improvements were not dependent on genotype, we noted larger mean differences in ppFEV1, BMI, pulmonary exacerbations and antibiotic use in the group with more severe lung disease (ppFEV1 <80 %) after one year of ETI therapy.

CONCLUSION

ETI therapy improved clinical outcomes in pwCF which were impacted by severity of underlying lung disease.

Proteomics profiling of inflammatory responses to elexacaftor/tezacaftor/ivacaftor in cystic fibrosis

Background

CFTR modulator therapies have positive clinical outcomes, yet chronic inflammation and bacterial infections persist in people with CF (pwCF). How elexacaftor-tezacaftor-ivacaftor (ETI) fails to improve innate immune signaling responsible for bacterial clearance and inflammation resolution remains unknown.

Methods

We used an unbiased proteomics approach to measure the effect of ETI on inflammatory proteins. Plasma from 20 pediatric pwCF and 20 non-CF (NCF) was collected during routine examination and 3 months after ETI initiation. Protein screening was performed with an inflammation panel (Target 96, Olink®). Bioinformatics analysis was used to determine changes in protein expression.

Results

There were significantly fewer pulmonary exacerbations after ETI initiation, along with sustained improvement in lung function and reduced bacterial colonization. Unpaired analysis of CF pre-ETI and NCF resulted in 34 significantly different proteins. Of these, CCL20, MMP-10, EN-RAGE, and AXIN1 had a log2 fold change of 1.2 or more. There was a modest shift in overall CF protein profiles post-ETI toward the NCF cluster. Unpaired analysis of protein differential expression between NCF and CF post-ETI identified a total of 24 proteins significantly impacted by ETI therapy (p-value ≤ 0.05), with only CCL20 having a log2 fold change higher than 1.2. Paired analysis (CF pre- and CF post-ETI) of differential protein expression demonstrated significant expression changes of MMP-10, EN-RAGE, and IL-17A. Pathway analysis identified significantly impacted pathways such as the NF-κB pathway.

Conclusion

This study showed that ETI in a pediatric cohort had a modest effect on several inflammatory proteins with potential as biomarkers. Pathways significantly impacted by ETI can be further studied for future therapies to combat persistent inflammation and dysregulated immunity.

Elexacaftor/tezacaftor/ivacaftor and inflammation in children and adolescents with cystic fibrosis: a retrospective dual-center cohort study

BACKGROUND

Cystic fibrosis (CF) is characterized by chronic neutrophilic inflammation in the airways. Elexacaftor/tezacaftor/ivacaftor (ETI) therapy has demonstrably improved clinical outcomes and quality of life in people with CF (pwCF), but its effects on systemic inflammatory parameters remain unclear.

OBJECTIVE

To evaluate the impact of ETI on systemic inflammation in children and adolescents with CF.

DESIGN

Retrospective, dual-center observational, propensity score-matching study of pediatric pwCF on ETI.

METHODS

PwCF aged ⩽ 18 years treated with ETI at two Italian reference centers were included in this study. Data on immunoglobulins (Ig) (A, G, and M), γ-globulin, leukocyte levels, percent predicted forced expiratory volume in the first second (ppFEV1), sweat chloride (SC) concentration, and sputum cultures were collected at baseline, 12, and 24 months of treatment. Laboratory data of a control group (pwCF, not in ETI therapy, same demographic characteristics as the study group) were also collected.

RESULTS

Sixty-six patients (30 males, median age: 12 years, F508del homozygous: 23) were included. Mean IgG levels (SD) significantly decreased (p = 0.001) from 1168.20 mg/dl (344.41) at baseline to 1093.05 mg/dl (258.73; 12 months) and 1092.87 mg/dl (232.42; 24 months). Similar reductions were observed for IgA and γ-globulin; IgM reduction was not statistically significant. Leukocyte levels also decreased significantly from 8.04 × 103/µl (3.23 × 103) at baseline to 6.61 × 103/µl (1.74 × 103) (12 months) and 6.45 × 103/µl (1.70 × 103; 24 months). As for the control group, no significant changes in the levels of Ig, leukocytes, and γ-globulin were detected throughout the study period (p > 0.05).The mean (SD) ppFEV1 and the overall mean (SD) SC concentration significantly decreased during the follow-up. Regarding cultures, 18 (27%) of the 27 patients positive (41%) for Staphylococcus aureus at baseline became negative during treatment. Three patients (4%) with persistently positive cultures for Pseudomonas aeruginosa during the first 12 months, became negative after 24 months. One patient (1.5%), with a baseline positive culture for Pseudomonas Aeruginosa, showed negative cultures after 12 months.

CONCLUSION

ETI treatment improved respiratory outcomes and significantly reduced values of IgG, IgA, γ-globulin, and leukocytes, suggesting an effect on the systemic inflammatory response. Further research is warranted to elucidate the role of inflammatory parameters in monitoring response to therapy.

Outcomes of Modulator Therapy Discontinued After Short-Term Use in Adult Cystic Fibrosis

INTRODUCTION

Cystic fibrosis transmembrane conductance regulator modulator therapies (CFTR-MT) have altered management, reducing exacerbations and slowing pulmonary function decline. Nevertheless, it is still uncertain if the benefits of CFTR-MTs last when they are stopped. This study aimed to assess pulmonary function changes, and exacerbation rates during and after CFTR-MT use in adult cystic fibrosis patients.

METHODS

Between 2018 and 2022, we conducted a study involving adult CF patients who initially used CFTR-MTs but later discontinued them due to reimbursement issues. The study was divided into three phases: predrug (T1), in-drug (T2), and postdrug (T3). We recorded pulmonary function tests, laboratory and culture results, and the number of exacerbations.

RESULTS

The study involved 33 patients, with 28 (84.8%) receiving Elexacaftor/Tezacaftor/Ivacaftor and 5 (15.2%) receiving Ivacaftor. The median treatment and interruption durations were 3.1 (IQR = 2.9-5.7), and 2.5 (IQR = 1.5-4.0) months, respectively. The mean FEV1% was 54.3% (± 26.6), 70.4% (± 27.4), and 60.2% (± 26.5) during T1, T2, and T3, respectively (p < 0.001). The mean FVC% was 65.5% (± 23.9) in T1, increased to 81.5% (± 24.5) in T2, and decreased to 71.6% (± 25.9) in T3 (p < 0.001). The number of Psedomonas aeruginosa, and Aspergillus positive sputum cultures decreased significantly with drug use (T1: 72.7%, 39.4%; T2: 48.5%, 9.1%; T3: 45.5%, 18.2%; p = 0.014, p = 0.004, respectively). The median number of hospitalizations was 1.0 (0-5.0) in T1, 0 (0-0) in T2, and 0 (0-1.0) in T3.

CONCLUSION

This study revealed that CFTR-MTs are effective even in the short term for adult CF patients, but their beneficial effects quickly diminish after discontinuation. Real-life data obtained as a result of discontinuation of drugs due to reimbursement problems has highlighted the significance of regular and uninterrupted use of modulators.

Gene expression responses of CF airway epithelial cells exposed to elexacaftor/tezacaftor/ivacaftor suggest benefits beyond improved CFTR channel function

The combination of elexacaftor/tezacaftor/ivacaftor (ETI, Trikafta) reverses the primary defect in cystic fibrosis (CF) by improving CFTR-mediated Cl- and HCO3- secretion by airway epithelial cells (AECs), leading to improved lung function and less frequent exacerbations and hospitalizations. However, studies have shown that CFTR modulators like ivacaftor, a component of ETI, have numerous effects on CF cells beyond improved CFTR channel function. Because little is known about the effect of ETI on CF AEC gene expression, we exposed primary human AEC to ETI for 48 h and interrogated the transcriptome by RNA-seq and qPCR. ETI increased CFTR Cl- secretion, and defensin gene expression (DEFB1), an observation consistent with reports of decreased bacterial burden in the lungs of people with CF (pwCF). ETI decreased MMP10 and MMP12 gene expression, suggesting that ETI may reduce proteolytic-induced lung destruction in CF. ETI also reduced the expression of the stress response gene heme oxygenase (HMOX1). qPCR analysis confirmed DEFB1, HMOX1, MMP10, and MMP12 gene expression results observed by RNA-seq. Gene pathway analysis revealed that ETI decreased inflammatory signaling, cellular proliferation, and MHC class II antigen presentation. Collectively, these findings suggest that the clinical observation that ETI reduces lung infections in pwCF is related in part to drug-induced increases in DEFB1 and that ETI may reduce lung damage by reducing MMP10 and MMP12 gene expression. Moreover, pathway analysis also identified several other genes responsible for the ETI-induced reduction in inflammation observed in pwCF.NEW & NOTEWORTHY Gene expression responses by CF AECs exposed to ETI suggest that in addition to improving CFTR channel function, ETI is likely to enhance resistance to bacterial infection by increasing levels of beta-defensin 1 (hBD-1). ETI may also reduce lung damage by suppressing MMP10 and MMP12 and reduce airway inflammation by repressing proinflammatory cytokine secretion by CF AECs.

One year of ETI reduces lung bacterial colonisation in adults with cystic fibrosis

The triple combination elexacaftor-tezacaftor-ivacaftor (ETI) has provided unprecedented clinical benefits for people with cystic fibrosis (pwCF) and drastically transformed the outcome of this disease. We aimed to describe the evolution of lung bacterial colonization in 198 French adult pwCF taking into account the use of concomitantly respiratory treatment. We collected sputum cultures produced during the entire follow-up period starting 3 years before and ending 1 year after ETI initiation. All sputum cultures were centralized and analyzed at our bacteriological laboratory. Clinical data included pulmonary function, respiratory treatments, physiotherapy, number of IV antibiotics treatment, as well as inpatient stays. We observed a significant decrease in colonization prevalence by any CF pathogen after one year of treatment with ETI (p < 0.001). This decrease was confirmed for Pseudomonas aeruginosa, MRSA and MSSA, Stenotrophomonas maltophilia, Achromobacter spp. and nontuberculous mycobacteria (NTM). The maximal density of bacteria documented in sputum cultures decreased from 2.107 CFU/ml to 1.106 CFU/ml after one year of ETI. We also found a decrease in prevalence of Pseudomonas aeruginosa chronic colonization and in the density of Pseudomonas aeruginosa after one year of ETI. These results confirm the decrease in prevalence and bacterial density of lung colonisation for most of the CF pathogens, including Achromobacter spp, Stenotrophomonas maltophilia concomitantly to the clinical improvement. Further studies are needed to better understand the underlying mechanisms of these microbiological changes.

Seasonal and climatic influence on respiratory infections in children with cystic fibrosis

Pseudomonas aeruginosa (Pa) and Methicillin susceptible Staphylococcus aureus (MSSA) are the predominant bacteria found in the airways of people with cystic fibrosis (pwCF), significantly contributing to lung disease progression. While various factors influencing the initial acquisition (IA) of these pathogens are known, the impact of environmental conditions remains understudied. This epidemiological study assessed the risk of MSSA and Pa initial acquisitions in relation to seasonality and climatic zones among 1,184 French pwCF under 18 years old. The age at IA for Pa (Pa-IA) and MSSA (MSSA-IA) was estimated using the Kaplan-Meier method. Seasonality and climatic zones were analysed as risk factors using time-varying Cox regression models. The median age at MSSA-IA was notably earlier (2.0 years) than that at Pa-IA (5.1 years). MSSA-IA occurred increasingly younger in more recent birth cohorts, while the age at Pa-IA remained stable over time. The risk of Pa-IA was consistently higher in all seasons compared with spring, peaking in autumn (HR = 1.53), irrespective of climatic zones. In Oceanic and Continental climates, the highest risk for MSSA-IA was in winter (HRs = 1.45 and 1.20 respectively). In the Mediterranean climate, the risk of MSSA-IA was lower in winter compared to spring (HRs = 0.68 and 0.61 respectively), and the median age at MSSA-IA later than for Pa-IA. This study demonstrates that seasonality and meteorological factors may influence acquisition of MSSA and Pa in pwCF. These findings suggest that environmental factors play a role in pathogen acquisition dynamics in CF and could inform the development of preventive strategies.

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.

Impact of CFTR Modulation on Pseudomonas aeruginosa Infection in People With Cystic Fibrosis

BACKGROUND

Pseudomonas aeruginosa is a multidrug-resistant pathogen causing recalcitrant pulmonary infections in people with cystic fibrosis (pwCF). Cystic fibrosis transmembrane conductance regulator (CFTR) modulators have been developed that partially correct the defective chloride channel driving disease. Despite the many clinical benefits, studies in adults have demonstrated that while P. aeruginosa sputum load decreases, chronic infection persists. Here, we investigate how P. aeruginosa in pwCF may change in the altered lung environment after CFTR modulation.

METHODS

P. aeruginosa strains (n = 105) were isolated from the sputum of 11 chronically colonized pwCF at baseline and up to 21 months posttreatment with elexacaftor-tezacaftor-ivacaftor or tezacaftor-ivacaftor. Phenotypic characterization and comparative genomics were performed.

RESULTS

Clonal lineages of P. aeruginosa persisted after therapy, with no evidence of displacement by alternative strains. We identified commonly mutated genes among patient isolates that may be positively selected for in the CFTR-modulated lung. However, classic chronic P. aeruginosa phenotypes such as mucoid morphology were sustained, and isolates remained just as resistant to clinically relevant antibiotics.

CONCLUSIONS

Despite the clinical benefits of CFTR modulators, clonal lineages of P. aeruginosa persist that may prove just as difficult to manage in the future, especially in pwCF with advanced lung disease.

The continuing need for dornase alfa for extracellular airway DNA hydrolysis in the era of CFTR modulators

INTRODUCTION

The availability of cystic fibrosis transmembrane conductance regulator (CFTR) modulators opens the possibility of discontinuing some chronic pulmonary therapies to decrease cystic fibrosis (CF) treatment burden. However, CFTR modulators may not adequately address neutrophilic inflammation, which contributes to a self-perpetual cycle of viscous CF sputum, airway obstruction, inflammation, and lung function decline.

AREAS COVERED

This review discusses the emerging role of neutrophil extracellular traps in CF and its role in CF sputum viscosity, airway obstruction, and inflammation, based on a literature search of PubMed (1990-present). We summarize clinical trials and real-world studies that support the efficacy of dornase alfa (Pulmozyme) in improving lung function and reducing pulmonary exacerbation in people with CF (PwCF), and we discuss the potential role of dornase alfa in reducing airway inflammation. We also examine the findings of short-term trials evaluating the discontinuation of mucoactive therapy in PwCF receiving CFTR modulators.

EXPERT OPINION

Long-term studies are needed to assess the impact of discontinuing mucoactive therapy in PwCF who are clinically stable while receiving CFTR modulatory therapy. Treatment decisions should take into account the severity of underlying lung disease. People with advanced CF will likely require ongoing mucoactive therapy.

Gene expression responses of CF airway epithelial cells exposed to elexacaftor/tezacaftor/ivacaftor (ETI) suggest benefits beyond improved CFTR channel function

The combination of elexacaftor/tezacaftor/ivacaftor (ETI, Trikafta) reverses the primary defect in Cystic Fibrosis (CF) by improving CFTR mediated Cl - and HCO 3 - secretion by airway epithelial cells (AEC), leading to improved lung function and less frequent exacerbations and hospitalizations. However, studies have shown that CFTR modulators like ivacaftor, a component of ETI, has numerous effects on CF cells beyond improved CFTR channel function. Because little is known about the effect of ETI on CF AEC gene expression we exposed primary human AEC to ETI for 48 hours and interrogated the transcriptome by RNA-seq and qPCR. ETI increased defensin gene expression ( DEFB1 ) an observation consistent with reports of decreased bacterial burden in the lungs of people with CF (pwCF). ETI also decreased MMP10 and MMP12 gene expression, suggesting that ETI may reduce proteolytic induced lung destruction in CF. ETI also reduced the expression of the stress response gene heme oxygenase ( HMOX1 ). qPCR analysis confirmed DEFB1, HMOX1, MMP10 and MMP12 gene expression results observed by RNA-seq. Gene pathway analysis revealed that ETI decreased inflammatory signaling, cellular proliferation and MHC Class II antigen presentation. Collectively, these findings suggest that the clinical observation that ETI reduces lung infections in pwCF is related in part to drug induced increases in DEFB1 , and that ETI may reduce lung damage by reducing MMP10 and MMP12 gene expression, which is predicted to reduce matrix metalloprotease activity. Moreover, pathway analysis also identified several genes responsible for the ETI induced reduction in inflammation observed in people with CF.

New and Noteworthy

Gene expression responses by CF AEC exposed to ETI suggest that in addition to improving CFTR channel function, ETI is likely to increase resistance to bacterial infection by increasing levels of beta defensin 1 (hBD-1). ETI may also reduce lung damage by suppressing MMP10, and reduce airway inflammation by repressing proinflammatory cytokine secretion by AEC cells.

Pseudomonas aeruginosa in chronic lung disease: untangling the dysregulated host immune response

Pseudomonas aeruginosa is a highly adaptable opportunistic pathogen capable of exploiting barriers and immune defects to cause chronic lung infections in conditions such as cystic fibrosis. In these contexts, host immune responses are ineffective at clearing persistent bacterial infection, instead driving a cycle of inflammatory lung damage. This review outlines key components of the host immune response to chronic P. aeruginosa infection within the lung, beginning with initial pathogen recognition, followed by a robust yet maladaptive innate immune response, and an ineffective adaptive immune response that propagates lung damage while permitting bacterial persistence. Untangling the interplay between host immunity and chronic P. aeruginosa infection will allow for the development and refinement of strategies to modulate immune-associated lung damage and potentiate the immune system to combat chronic infection more effectively.

Effect of Modulator Therapies on Nutritional Risk Index in Adults with Cystic Fibrosis: A Prospective Cohort Study

Background: Modulator therapies improve weight and body mass index (BMI) in cystic fibrosis (CF) patients. We aimed to compare the nutritional risk index (NRI) in adult CF patients receiving modulator (MT) or only non-modulator (conventional) therapies (non-MT). Methods: A single-center prospective cohort study was conducted between June and December 2023. The NRI based on weight gain and albumin was calculated at beginning and end of a 12-week period in both groups. This design was pragmatic, since it was based on individual patient access to MT for 12 weeks. Results: In total, 107 patients were included [mean (SD) age: 23.85 (4.98) years, 54.7% male, 46.7% MT]. In the MT group, mean (SD) weight (kg) and albumin (g/dL) increased significantly [changes: +3.09 (2.74) and +0.17 (0.37); p < 0.001]. In the non-MT group, weight and albumin decreased significantly [changes: -0.99 (1.73) and -0.12 (0.30); p < 0.001]. Compared to the MT group, baseline mean (SD) NRI in the non-MT group was significantly higher [100.65 (11.80) vs. 104.10 (10.10); p = 0.044]. At the end of the 12 weeks, mean (SD) NRI in the MT group was higher than in the non-MT group [104.18 (10.40) vs. 102.58 (12.39); p = 0.145]. In the MT group, the NRI category improved in 22 (44%), and worsened in 3 (6%) patients (p < 0.001). In the non-MT group, the NRI category improved in 2 (3.5%), and worsened in 10 (17.5%) patients (p < 0.001). Conclusions: This is the first study reporting on a positive effect of MT on NRIs, based on weight gain and albumin. Personalized nutrition and routine follow-up of adults with CF based on NRI is recommended prior to MT initiation.

Analysis of CFTR mRNA and Protein in Peripheral Blood Mononuclear Cells via Quantitative Real-Time PCR and Western Blot

The Cystic Fibrosis Conductance Transmembrane Regulator gene encodes for the CFTR ion channel, which is responsible for the transport of chloride and bicarbonate across the plasma membrane. Mutations in the gene result in impaired ion transport, subsequently leading to perturbed secretion in all exocrine glands and, therefore, the multi-organ disease cystic fibrosis (CF). In recent years, several studies have reported on CFTR expression in immune cells as demonstrated by immunofluorescence, flow cytometry, and immunoblotting. However, these data are mainly restricted to single-cell populations and show significant variation depending on the methodology used. Here, we investigated CFTR transcription and protein expression using standardized protocols in a comprehensive panel of immune cells. Methods: We applied a high-resolution Western blot protocol using a combination of highly specific monoclonal CFTR antibodies that have been optimized for the detection of CFTR in epithelial cells and healthy primary immune cell subpopulations sorted by flow cytometry and used immortalized cell lines as controls. The specificity of CFTR protein detection was controlled by peptide competition and enzymatic Peptide-N-Glycosidase-F (PNGase) digest. CFTR transcripts were analyzed using quantitative real-time PCR and normalized to the level of epithelial T84 cells as a reference. Results: CFTR mRNA expression could be shown for primary CD4+ T cells, NK cells, as well as differentiated THP-1 and Jurkat T cells. In contrast, we failed to detect CFTR transcripts for CD14+ monocytes and undifferentiated THP-1 cells, as well as for B cells and CD8+ T cells. Prominent immunoreactive bands were detectable by immunoblotting with the combination of four CFTR antibodies targeting different epitopes of the CFTR protein. However, in biosamples of non-epithelial origin, these CFTR-like protein bands could be unmasked as false positives through peptide competition or PNGase digest, meaning that the observed mRNA transcripts were not necessarily translated into CFTR proteins, which could be detected via immunoblotting. Our results confirm that mRNA expression in immune cells is many times lower than in that cells of epithelial origin. The immunoreactive signals in immune cells turned out to be false positives, and may be provoked by the presence of a high-affinity protein with a similar epitope. Non-specific binding (e.g., Fab-interaction with glycosyl branches) might also contribute to false positive signals. Our findings highlight the necessity of accurate controls, such as CFTR-negative cells, as well as peptide competition and glycolytic digest in order to identify genuine CFTR protein by immunoblotting. Our data suggest, furthermore, that CFTR protein expression data from techniques such as histology, for which the absence of a molecular weight or other independent control prevents the unmasking of false positive immunoreactive signals, must be interpreted carefully as well.

Innate immune responses are increased in children with acute asthma exacerbation

BACKGROUND

Little is known about the immune responses during acute asthma exacerbation. In this study, we examined immune responses in children following an acute asthma exacerbation.

METHODS

We evaluated pro-inflammatory cytokine levels and gene expression profiles in blood samples from pediatric patients admitted for acute asthma exacerbation. Viral PCR was performed to differentiate between viral or non-viral-associated exacerbations.

RESULTS

Following informed consent, clinical data were obtained from 20 children with asthma (median [interquartile range, IQR]: age 11.5 [8.0, 14.2]) years and 14 healthy age-matched controls (10.5 [7.0, 13.0]). Twelve had positive nasopharyngeal Polymerase chain reaction (PCR) for viral infection (11 rhinoviruses and 1 respiratory syncytial virus (RSV)). Nine were in the pediatric intensive care unit (PICU) and among them five required continuous positive airway pressure (CPAP). Mean (±SD) days on systemic steroids before drawing blood sample were 2.5 ± 1.6. Twelve had history of environmental allergies with 917 (274, 1396) IU/mL total IgE (median (IQR)). Compared with controls, IL-1RA and IL-10 levels were significantly increased and TNF-α significantly decreased in asthma subjects (p < .05 for all). RNA-seq analysis revealed 852 differentially expressed genes in subjects with asthma. Pathway analysis found upregulated genes and pathways involved in innate immune responses in subjects with asthma. Significantly reduced genes included pathways associated with T helper cell differentiation and activation.

CONCLUSIONS

In acute asthma exacerbation, innate immune pathways remained increased while adaptive immune responses related to T helper cells are blunted and are independent of trigger or asthma severity. Our novel findings highlight the need to identify new therapies to target persistent innate immune responses to improve outcomes in acute asthma.

Anti-inflammatory effects of elexacaftor/tezacaftor/ivacaftor in adults with cystic fibrosis heterozygous for F508del

Inflammation is a key driver in the pathogenesis of cystic fibrosis (CF). We assessed the effectiveness of elexacaftor/tezacaftor/ivacaftor (ETI) therapy on downregulating systemic and immune cell-derived inflammatory cytokines. We also monitored the impact of ETI therapy on clinical outcome. Adults with CF, heterozygous for F508del (n = 19), were assessed at baseline, one month and three months following ETI therapy, and clinical outcomes were measured, including sweat chloride, lung function, weight, neutrophil count and C-reactive protein (CRP). Cytokine quantifications were measured in serum and following stimulation of peripheral blood mononuclear cells (PBMCs) with lipopolysaccharide (LPS) and adenosine triphosphate and analysed using LEGEND plex™ Human Inflammation Panel 1 by flow cytometry (n = 19). ASC specks were measured in serum and caspase-1 activity and mRNA levels determined from stimulated PBMCs were determined. Patients remained stable over the study period. ETI therapy resulted in decreased sweat chloride concentrations (p < 0.0001), CRP (p = 0.0112) and neutrophil count (p = 0.0216) and increased percent predicted forced expiratory volume (ppFEV1) (p = 0.0399) from baseline to three months, alongside a trend increase in weight. Three months of ETI significantly decreased IL-18 (p< 0.0011, p < 0.0001), IL-1β (p<0.0013, p = 0.0476), IL-6 (p = 0.0109, p = 0.0216) and TNF (p = 0.0028, p = 0.0033) levels in CF serum and following PBMCs stimulation respectively. The corresponding mRNA levels were also found to be reduced in stimulated PBMCs, as well as reduced ASC specks and caspase-1 levels, indicative of NLRP3-mediated production of pro-inflammatory cytokines, IL-1β and IL-18. While ETI therapy is highly effective at reducing sweat chloride and improving lung function, it also displays potent anti-inflammatory properties, which are likely to contribute to improved long-term clinical outcomes.

Persistence and evolution of Pseudomonas aeruginosa following initiation of highly effective modulator therapy in cystic fibrosis

Today, more than 90% of people with cystic fibrosis (pwCF) are eligible for the highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy called elexacaftor/tezacaftor/ivacaftor (ETI) and its use is widespread. Given the drastic respiratory symptom improvement experienced by many post-ETI, clinical studies are already underway to reduce the number of respiratory therapies, including antibiotic regimens, that pwCF historically relied on to combat lung disease progression. Early studies suggest that bacterial burden in the lungs is reduced post-ETI, yet it is unknown how chronic Pseudomonas aeruginosa populations are impacted by ETI. We found that pwCF remain infected throughout their upper and lower respiratory tract with their same strain of P. aeruginosa post-ETI, and these strains continue to evolve in response to the newly CFTR-corrected airway. Our work underscores the continued importance of CF airway microbiology in the new era of highly effective CFTR modulator therapy.

IMPORTANCE

The highly effective cystic fibrosis transmembrane conductance regulator modulator therapy Elexakaftor/Tezacaftor/Ivacaftor (ETI) has changed cystic fibrosis (CF) disease for many people with cystic fibrosis. While respiratory symptoms are improved by ETI, we found that people with CF remain infected with Pseudomonas aeruginosa. How these persistent and evolving bacterial populations will impact the clinical manifestations of CF in the coming years remains to be seen, but the role and potentially changing face of infection in CF should not be discounted in the era of highly effective modulator therapy.

Ligand-based virtual-screening identified a novel CFTR ligand which improves the defective cell surface expression of misfolded ABC transporters

Cystic fibrosis (CF) is a monogenetic disease caused by the mutation of CFTR, a cAMP-regulated Cl- channel expressing at the apical plasma membrane (PM) of epithelia. ∆F508-CFTR, the most common mutant in CF, fails to reach the PM due to its misfolding and premature degradation at the endoplasmic reticulum (ER). Recently, CFTR modulators have been developed to correct CFTR abnormalities, with some being used as therapeutic agents for CF treatment. One notable example is Trikafta, a triple combination of CFTR modulators (TEZ/ELX/IVA), which significantly enhances the functionality of ΔF508-CFTR on the PM. However, there's room for improvement in its therapeutic effectiveness since TEZ/ELX/IVA doesn't fully stabilize ΔF508-CFTR on the PM. To discover new CFTR modulators, we conducted a virtual screening of approximately 4.3 million compounds based on the chemical structures of existing CFTR modulators. This effort led us to identify a novel CFTR ligand named FR3. Unlike clinically available CFTR modulators, FR3 appears to operate through a distinct mechanism of action. FR3 enhances the functional expression of ΔF508-CFTR on the apical PM in airway epithelial cell lines by stabilizing NBD1. Notably, FR3 counteracted the degradation of mature ΔF508-CFTR, which still occurs despite the presence of TEZ/ELX/IVA. Furthermore, FR3 corrected the defective PM expression of a misfolded ABCB1 mutant. Therefore, FR3 may be a potential lead compound for addressing diseases resulting from the misfolding of ABC transporters.

Nasal airway inflammatory responses and pathogen detection in infants with cystic fibrosis

BACKGROUND

Detecting airway inflammation non-invasively in infants with cystic fibrosis (CF) is difficult. We hypothesized that markers of inflammation in CF [IL-1β, IL-6, IL-8, IL-10, IL-17A, neutrophil elastase (NE) and tumor necrosis factor (TNF-α)] could be measured in infants with CF from nasal fluid and would be elevated during viral infections or clinician-defined pulmonary exacerbations (PEx).

METHODS

We collected nasal fluid, nasal swabs, and hair samples from 34 infants with CF during monthly clinic visits, sick visits, and hospitalizations. Nasal fluid was isolated and analyzed for cytokines. Respiratory viral detection on nasal swabs was performed using the Luminex NxTAG® Respiratory Pathogen Panel. Hair samples were analyzed for nicotine concentration by reverse-phase high-performance liquid chromatography. We compared nasal cytokine concentrations between the presence and absence of detected respiratory viruses, PEx, and smoke exposure.

RESULTS

A total of 246 samples were analyzed. Compared to measurements in the absence of respiratory viruses, mean concentrations of IL-6, IL-8, TNF-α, and NE were significantly increased while IL-17A was significantly decreased in infants positive for respiratory viruses. IL-17A was significantly decreased and NE increased in those with a PEx. IL-8 and NE were significantly increased in infants with enteric pathogen positivity on airway cultures, but not P. aeruginosa or S. aureus. Compared to those with no smoke exposure, there were significantly higher levels of IL-6, IL-10, and NE in infants with detectable levels of nicotine.

CONCLUSIONS

Noninvasive collection of nasal fluid may identify inflammation in infants with CF during changing clinical or environmental exposures.

CFTR is required for zinc-mediated antibacterial defense in human macrophages

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion transporter required for epithelial homeostasis in the lung and other organs, with CFTR mutations leading to the autosomal recessive genetic disease CF. Apart from excessive mucus accumulation and dysregulated inflammation in the airways, people with CF (pwCF) exhibit defective innate immune responses and are susceptible to bacterial respiratory pathogens such as Pseudomonas aeruginosa. Here, we investigated the role of CFTR in macrophage antimicrobial responses, including the zinc toxicity response that is used by these innate immune cells against intracellular bacteria. Using both pharmacological approaches, as well as cells derived from pwCF, we show that CFTR is required for uptake and clearance of pathogenic Escherichia coli by CSF-1-derived primary human macrophages. CFTR was also required for E. coli-induced zinc accumulation and zinc vesicle formation in these cells, and E. coli residing in macrophages exhibited reduced zinc stress in the absence of CFTR function. Accordingly, CFTR was essential for reducing the intramacrophage survival of a zinc-sensitive E. coli mutant compared to wild-type E. coli. Ectopic expression of the zinc transporter SLC30A1 or treatment with exogenous zinc was sufficient to restore antimicrobial responses against E. coli in human macrophages. Zinc supplementation also restored bacterial killing in GM-CSF-derived primary human macrophages responding to P. aeruginosa, used as an in vitro macrophage model relevant to CF. Thus, restoration of the zinc toxicity response could be pursued as a therapeutic strategy to restore innate immune function and effective host defense in pwCF.

Use of elexacaftor/tezacaftor/ivacaftor leads to changes in detection frequencies of Staphylococcus aureus and Pseudomonas aeruginosa dependent on age and lung function in people with cystic fibrosis

OBJECTIVES

The impressive improvements of cystic fibrosis (CF) transmembrane conductance regulator (CFTR) function by elexacaftor/tezacaftor/ivacaftor (ETI) result in changes in the detection frequencies of Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA). We assessed determinants of the response to ETI with regards to SA and PA detection frequencies as documented in the German CF registry for people with CF (pwCF) ≥12 years.

METHODS

We evaluated changes in the detection frequencies of SA and PA for 21 months before and after initiation of ETI and used different statistical tests to identify determinants of detection changes.

RESULTS

We included data from 1092 pwCF with results from culture-dependent diagnostics for SA and PA detection from 7944 microbiological samples before and 6.845 microbiological samples after initiation of ETI. Detections of SA decreased from 54.3% to 44.3% and 40.2% and those of PA from 39.9% to 31.9% and 22.6% 3 and 21 months after initiation of therapy, respectively (all P <0.001). Reduction of SA and PA were observed in throat swabs and sputa, associated significantly with age, previous lung function, and were dependent on pre-ETI colonization status.

CONCLUSIONS

The different patterns of reductions of SA and PA suggest that pathogen-specific biological processes govern the responsiveness of microbiological colonization towards ETI in pwCF.

Diminished airway host innate response in people with cystic fibrosis who experience frequent pulmonary exacerbations

RATIONALE

Pulmonary exacerbations are clinically impactful events that accelerate cystic fibrosis (CF) lung disease progression. The pathophysiological mechanisms underlying an increased frequency of pulmonary exacerbations have not been explored.

OBJECTIVES

To compare host immune response during intravenous antibiotic treatment of pulmonary exacerbations in people with CF who have a history of frequent versus infrequent exacerbations.

METHODS

Adults with CF were recruited at onset of antibiotic treatment of a pulmonary exacerbation and were categorised as infrequent or frequent exacerbators based on their pulmonary exacerbation frequency in the previous 12 months. Clinical parameters, sputum bacterial load and sputum inflammatory markers were measured on day 0, day 5 and at the end of treatment. Shotgun proteomic analysis was performed on sputum using liquid chromatography-mass spectrometry.

MEASUREMENTS AND MAIN RESULTS

Many sputum proteins were differentially enriched between infrequent and frequent exacerbators (day 0 n=23 and day 5 n=31). The majority of these proteins had a higher abundance in infrequent exacerbators and were secreted innate host defence proteins with antimicrobial, antiprotease and immunomodulatory functions. Several differentially enriched proteins were validated using ELISA and Western blot including secretory leukocyte protease inhibitor (SLPI), lipocalin-1 and cystatin SA. Sputum from frequent exacerbators demonstrated potent ability to cleave exogenous recombinant SLPI in a neutrophil elastase dependent manner. Frequent exacerbators had increased sputum inflammatory markers (interleukin (IL)-1β and IL-8) and total bacterial load compared to infrequent exacerbators.

CONCLUSIONS

A diminished innate host protein defence may play a role in the pathophysiological mechanisms of frequent CF pulmonary exacerbations. Frequent exacerbators may benefit from therapies targeting this dysregulated host immune response.

MEK1/2 inhibition decreases pro-inflammatory responses in macrophages from people with cystic fibrosis and mitigates severity of illness in experimental murine methicillin-resistant Staphylococcus aureus infection

Chronic pulmonary bacterial infections and associated inflammation remain a cause of morbidity and mortality in people with cystic fibrosis (PwCF) despite new modulator therapies. Therapies targeting host factors that dampen detrimental inflammation without suppressing immune responses critical for controlling infections remain limited, while the development of lung infections caused by antimicrobial resistant bacteria is an increasing global problem, and a significant challenge in CF. Pharmacological compounds targeting the mammalian MAPK proteins MEK1 and MEK2, referred to as MEK1/2 inhibitor compounds, have potential combined anti-microbial and anti-inflammatory effects. Here we examined the immunomodulatory properties of MEK1/2 inhibitor compounds PD0325901, trametinib, and CI-1040 on CF innate immune cells. Human CF macrophage and neutrophil phagocytic functions were assessed by quantifying phagocytosis of serum opsonized pHrodo red E. coli, Staphylococcus aureus, and zymosan bioparticles. MEK1/2 inhibitor compounds reduced CF macrophage pro-inflammatory cytokine production without impairing CF macrophage or neutrophil phagocytic abilities. Wild-type C57BL6/J and Cftr tm1kth (F508del homozygous) mice were used to evaluate the in vivo therapeutic potential of PD0325901 compared to vehicle treatment in an intranasal methicillin-resistant Staphylococcus aureus (MRSA) infection with the community-acquired MRSA strain USA300. In both wild-type and CF mice, PD0325901 reduced inflammation associated body mass loss. Wild-type mice treated with PD0325901 had significant reduction in neutrophil-mediated inflammation compared to vehicle treatment groups, with preserved clearance of bacteria in lung, liver, or spleen 1 day after infection in either wild-type or CF mouse models. In summary, this study provides the first data evaluating the therapeutic potential of MEK1/2 inhibitor to modulate CF immune cells and demonstrates that MEK1/2 inhibitors diminish pro-inflammatory responses without impairing host defense mechanisms required for acute pathogen clearance.

Positioning the preventive potential of microbiome treatments for cystic fibrosis in the context of current therapies

Antibiotics and cystic fibrosis transmembrane conductance regulator (CFTR) modulators play a pivotal role in cystic fibrosis (CF) treatment, but both have limitations. Antibiotics are linked to antibiotic resistance and disruption of the airway microbiome, while CFTR modulators are not widely accessible, and structural lung damage and pathogen overgrowth still occur. Complementary strategies that can beneficially modulate the airway microbiome in a preventive way are highly needed. This could be mediated via oral probiotics, which have shown some improvement of lung function and reduction of airway infections and exacerbations, as a cost-effective approach. However, recent data suggest that specific and locally administered probiotics in the respiratory tract might be a more targeted approach to prevent pathogen outgrowth in the lower airways. This review aims to summarize the current knowledge on the CF airway microbiome and possibilities of microbiome treatments to prevent bacterial and/or viral infections and position them in the context of current CF therapies.

Plasma levels of chemokines decrease during elexacaftor/tezacaftor/ivacaftor therapy in adults with cystic fibrosis

Background

Cystic fibrosis (CF) is associated with dysregulated immune responses, exaggerated inflammation and chronic infection. CF transmembrane conductance regulator (CFTR) modulator therapies directly target the underlying protein defects and resulted in significant clinical benefits for people with CF (pwCF). This study analysed the effects of triple CFTR modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI) on CF-associated inflammation, especially systemic chemokines.

Methods

A bead-based immunoassay was used to quantify proinflammatory chemokines (IL-8, IP-10, Eotaxin, TARC, RANTES, MIP-1α, MIP-1β, MIP-3α, MIG, ENA-78, GROα, I-TAC) in plasma samples from pwCF collected before, at three, and at six months after starting ETI therapy.

Results

Fifty-one pwCF (47 % female; mean age 32 ± 10.4 years) were included. At baseline, 67 % were already receiving CFTR modulator therapy with tezacaftor/ivacaftor or lumacaftor/ivacaftor. After initiation of ETI therapy there was a significant improvement in percent predicted forced expiratory volume in 1 s (+12.7 points, p < 0.001) and a significant decrease in sweat chloride levels (-53.6 %, p < 0.001). After 6 months' treatment with ETI therapy there were significant decreases in plasma levels of MIP-3α (-68.2 %, p = 0.018), GROα (-17.7 %, p = 0.013), ENA-78 (-16.3 %, p = 0.034) and I-TAC (-3.4 %, p = 0.032). IL-8 exhibited a reduction that did not reach statistical significance (-17.8 %, p = 0.057); levels of other assessed cytokines did not change significantly from baseline.

Conclusions

ETI appears to affect a distinct group of chemokines that are predominately associated with neutrophilic inflammation, demonstrating the anti-inflammatory properties of ETI therapy.

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.

Impact of lumacaftor/ivacaftor on the bacterial and fungal respiratory pathogens in cystic fibrosis: a prospective multicenter cohort study in Sweden

BACKGROUND

A significant decline in pulmonary exacerbation rates has been reported in CF patients homozygous for F508del treated with lumacaftor/ivacaftor. However, it is still unclear whether this reduction reflects a diminished microbiological burden.

OBJECTIVES

The aim of this study was to determine the impact of lumacaftor/ivacaftor on the bacterial and fungal burden.

DESIGN

The study is a prospective multicenter cohort study including 132 CF patients homozygous for F508del treated with lumacaftor/ivacaftor.

METHODS

Clinical parameters as well as bacterial and fungal outcomes 1 year after initiation of lumacaftor/ivacaftor were compared to data from 2 years prior to initiation of the treatment. Changes in the slope of the outcomes before and after the onset of treatment were assessed.

RESULTS

Lung function measured as ppFEV1 (p < 0.001), body mass index (BMI) in adults (p < 0.001), and BMI z-score in children (p = 0.007) were improved after initiation of lumacaftor/ivacaftor. In addition, the slope of the prevalence of Streptococcus pneumoniae (p = 0.007) and Stenotrophomonas maltophilia (p < 0.001) shifted from positive to negative, that is, became less prevalent, 1 year after treatment, while the slope for Candida albicans (p = 0.009), Penicillium spp (p = 0.026), and Scedosporium apiospermum (p < 0.001) shifted from negative to positive.

CONCLUSION

The current study showed a significant improvement in clinical parameters and a reduction of some of CF respiratory microorganisms 1 year after starting with lumacaftor/ivacaftor. However, no significant changes were observed for Pseudomonas aeruginosa, Staphylococcus aureus, or Aspergillus fumigatus, key pathogens in the CF context.

Efficacy and safety profile of elexacaftor-tezacaftor-ivacaftor triple therapy on cystic fibrosis: a systematic review and single arm meta-analysis

Background: Elexacaftor-Tezacaftor-Ivacaftor (ELE/TEZ/IVA) is believed to be an effective and well-tolerated treatment for cystic fibrosis (CF), but the exact efficacy and safety profile are still unknown. Objective: This study aimed to clarify the extent of functional restoration when patients are given with triple combination treatment and demonstrate the prevalence of adverse events, to evaluate the overall profile of ELE/TEZ/IVA on CF. Methods: A literature search was conducted in PubMed, Web of Science and Cochrane Library. Random effects single-arm meta-analysis was performed to decipher the basal characteristics of CF, the improvement and safety profile after ELE/TEZ/IVA treatment. Results: A total 53 studies were included in this analysis. For all the patients in included studies. 4 weeks after ELE/TEZ/IVA treatment, the increasement of percentage of predicted Forced Expiratory Volume in the first second (ppFEV1) was 9.23% (95%CI, 7.77%-10.70%), the change of percentage of predicted Forced Vital Capacity (ppFVC) was 7.67% (95%CI, 2.15%-13.20%), and the absolute change of Cystic Fibrosis Questionnaire-Revised (CFQ-R) score was 21.46 points (95%CI, 18.26-24.67 points). The Sweat chloride (SwCl) was significantly decreased with the absolute change of -41.82 mmol/L (95%CI, -44.38 to -39.25 mmol/L). 24 weeks after treatment, the increasement of ppFEV1 was 12.57% (95%CI, 11.24%-13.90%), the increasement of ppFVC was 10.44% (95%CI, 7.26%-13.63%), and the absolute change of CFQ-R score was 19.29 points (95%CI, 17.19-21.39 points). The SwCl was significantly decreased with the absolute change of -51.53 mmol/L (95%CI, -56.12 to -46.94 mmol/L). The lung clearance index2.5 (LCI2.5) was also decreased by 1.74 units (95%CI, -2.42 to -1.07 units). The body mass index increased by 1.23 kg/m2 (95%CI, 0.89-1.57 kg/m2). As for adverse events, 0.824 (95%CI, 0.769-0.879) occurred during ELE/TEZ/IVA period, while the incidence of severe adverse events was 0.066 (95%CI, 0.028-0.104). Conclusion: ELE/TEZ/IVA is a highly effective strategy and relatively safe for CF patients and needs to be sustained to achieve better efficacy. Systematic Review Registration: Identifier: CRD42023441840.

Neuropsychiatric adverse effects from CFTR modulators deserve a serious research effort

PURPOSE OF REVIEW

This review highlights the problem of neuropsychiatric adverse effects (AEs) associated with elexacaftor/tezacaftor/ivacaftor (ETI), current suboptimal mitigation approaches, a novel testable mechanistic hypothesis, and potential solutions requiring further research.

RECENT FINDINGS

Studies show that a minority of persons with cystic fibrosis (PwCF) initiating cystic fibrosis transmembrane conductance regulator (CFTR) modulators experience neuropsychiatric AEs including worsening mood, cognition, anxiety, sleep, and suicidality. The GABA-A receptor is a ligand-gated chloride channel, and magnetic resonance spectroscopy neuroimaging studies have shown that reduced GABA expression in rostral anterior cingulate cortex is associated with anxiety and depression. Recent research details the impact of peripheral inflammation and the gut-brain axis on central neuroinflammation. Plasma ETI concentrations and sweat chloride have been evaluated in small studies of neuropsychiatric AEs but not validated to guide dose titration or correlated with pharmacogenomic variants or safety/efficacy.

SUMMARY

Although ETI is well tolerated by most PwCF, some experience debilitating neuropsychiatric AEs. In some cases, these AEs may be driven by modulation of CFTR and chloride transport within the brain. Understanding biological mechanisms is a critical next step in identifying which PwCF are likely to experience AEs, and in developing evidence-based strategies to mitigate them, while retaining modulator efficacy.

Elexacaftor/Tezacaftor/Ivacaftor Improves Bronchial Artery Dilatation Detected by Magnetic Resonance Imaging in Patients with Cystic Fibrosis

Rationale: Magnetic resonance imaging (MRI) detects improvements in mucus plugging and bronchial wall thickening, but not in lung perfusion in patients with cystic fibrosis (CF) treated with elexacaftor/tezacaftor/ivacaftor (ETI). Objectives: To determine whether bronchial artery dilatation (BAD), a key feature of advanced lung disease, indicates irreversibility of perfusion abnormalities and whether BAD could be reversed in CF patients treated with ETI. Methods: A total of 59 adults with CF underwent longitudinal chest MRI, including magnetic resonance angiography twice, comprising 35 patients with CF (mean age, 31 ± 7 yr) before (MRI1) and after (MRI2) at least 1 month (mean duration, 8 ± 4 mo) on ETI therapy and 24 control patients with CF (mean age, 31 ± 7 yr) without ETI. MRI was assessed using the validated chest MRI score, and the presence and total lumen area of BAD were assessed with commercial software. Results: The MRI global score was stable in the control group from MRI1 to MRI2 (mean difference, 1.1 [-0.3, 2.4]; P = 0.054), but it was reduced in the ETI group (-10.1 [-0.3, 2.4]; P < 0.001). In the control and ETI groups, BAD was present in almost all patients at baseline (95% and 94%, respectively), which did not change at MRI2. The BAD total lumen area did not change in the control group from MRI1 to MRI2 (1.0 mm2 [-0.2, 2.2]; P = 0.099) but decreased in the ETI group (-7.0 mm2 [-8.9, -5.0]; P < 0.001). This decrease correlated with improvements in the MRI global score (r = 0.540; P < 0.001). Conclusions: Our data show that BAD may be partially reversible under ETI therapy in adult patients with CF who have established disease.

Neutrophil bactericidal activity and host defenses in cystic fibrosis: a narrative review

Background and Objective

Cystic fibrosis (CF) is a disorder that affects the cystic fibrosis transmembrane conductance regulator (CFTR). Without properly functioning CFTR channels, chloride does not exit respiratory epithelial cells, and consequently the mucus lining the surface of the cells becomes thick. This viscous mucus accumulates and causes abnormal function of the mucociliary apparatus, which can lead to bacterial colonization, infections with Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), and eventually lung damage. Recent studies have shown that the increased susceptibility to respiratory infections in CF patients may also be due to defects in neutrophil function, but the exact mechanism is uncertain.

Methods

The PubMed database was searched on February 10, 2023 and again on July 23, 2023 to compile a comprehensive list of clinical and experimental studies to evaluate neutrophil function in CF. The first search included a combination of MeSH terms: "cystic fibrosis" and "neutrophils/physiology". A separate second search included a combination of the MeSH terms: "neutrophils" and "cystic fibrosis transmembrane conductance regulator".

Key Content and Findings

Neutrophils from patients with CF have decreased transfer of chloride into phagolysosomes after bacterial ingestion and have dysregulated degranulation. This reduces the production of toxic oxidative radicals, especially hypochlorous acid (HOCl), and reduces bactericidal activity. CFTR potentiators correct the dysregulated degranulation in patients with CF and increased neutrophil killing activity. A reduced concentration of chloride in in vitro assays also reduces neutrophil killing activity; these observations are relevant to the reduced chloride concentrations in respiratory secretions in patients with CF.

Conclusions

This literature review summarizes studies that demonstrate that an important defect in CF neutrophils lies in the oxygen-dependent pathway in phagolysosomes and studies with ivacaftor demonstrate that this drug corrects CF neutrophil function. These studies demonstrate the potential utility of using easily available neutrophils to study drug effects in CF patients.

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.

Effect of elexacaftor/tezacaftor/ivacaftor on airway and systemic inflammation in cystic fibrosis

Treatment with elexacaftor/tezacaftor/ivacaftor (ETI) has been shown to improve lung function in people with cystic fibrosis (PWCF). However, its biological effects remain incompletely understood. Here we describe alterations in pulmonary and systemic inflammation in PWCF following initiation of ETI. To address this, we collected spontaneously expectorated sputum and matching plasma from PWCF (n=30) immediately prior to ETI therapy, then again at 3 and 12 months. Within 3 months, PWCF demonstrated reduced activity of neutrophil elastase, proteinase three and cathepsin G, and decreased concentrations of interleukin (IL)-1β and IL-8 in sputum, accompanied by decreased Pseudomonas burden and restoration of secretory leukoprotease inhibitor levels. Once treated with ETI, all airway inflammatory markers studied in PWCF had reduced to levels found in matched non-CF bronchiectasis controls. In PWCF with advanced disease, ETI resulted in decreased plasma concentrations of IL-6, C-reactive protein and soluble TNF receptor one as well as normalisation of levels of the acute phase protein, alpha-1 antitrypsin. These data clarify the immunomodulatory effects of ETI and underscore its role as a disease modifier.

Comparative effects of CFTR modulators on phagocytic, metabolic and inflammatory profiles of CF and nonCF macrophages

Macrophage dysfunction has been well-described in Cystic Fibrosis (CF) and may contribute to bacterial persistence in the lung. Whether CF macrophage dysfunction is related directly to Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) in macrophages or an indirect consequence of chronic inflammation and mucostasis is a subject of ongoing debate. CFTR modulators that restore CFTR function in epithelial cells improve global CF monocyte inflammatory responses but their direct effects on macrophages are less well understood. To address this knowledge gap, we measured phagocytosis, metabolism, and cytokine expression in response to a classical CF pathogen, Pseudomonas aeruginosa in monocyte-derived macrophages (MDM) isolated from CF F508del homozygous subjects and nonCF controls. Unexpectedly, we found that CFTR modulators enhanced phagocytosis in both CF and nonCF cohorts. CFTR triple modulators also inhibited MDM mitochondrial function, consistent with MDM activation. In contrast to studies in humans where CFTR modulators decreased serum inflammatory cytokine levels, modulators did not alter cytokine secretion in our system. Our studies therefore suggest modulator induced metabolic effects may promote bacterial clearance in both CF and nonCF monocyte-derived macrophages.

Furin as a therapeutic target in cystic fibrosis airways disease

Clinical management of cystic fibrosis (CF) has been greatly improved by the development of small molecule modulators of the CF transmembrane conductance regulator (CFTR). These drugs help to address some of the basic genetic defects of CFTR; however, no suitable CFTR modulators exist for 10% of people with CF (PWCF). An alternative, mutation-agnostic therapeutic approach is therefore still required. In CF airways, elevated levels of the proprotein convertase furin contribute to the dysregulation of key processes that drive disease pathogenesis. Furin plays a critical role in the proteolytic activation of the epithelial sodium channel; hyperactivity of which causes airways dehydration and loss of effective mucociliary clearance. Furin is also responsible for the processing of transforming growth factor-β, which is increased in bronchoalveolar lavage fluid from PWCF and is associated with neutrophilic inflammation and reduced pulmonary function. Pathogenic substrates of furin include Pseudomonas exotoxin A, a major toxic product associated with Pseudomonas aeruginosa infection and the spike glycoprotein of severe acute respiratory syndrome coronavirus 2, the causative pathogen for coronavirus disease 2019. In this review we discuss the importance of furin substrates in the progression of CF airways disease and highlight selective furin inhibition as a therapeutic strategy to provide clinical benefit to all PWCF.

Evolving Nutritional Needs in Cystic Fibrosis

The course of cystic fibrosis (CF) as a nutritional illness is diverging since the introduction of highly effective modulator therapy, leading to more heterogeneous phenotypes of the disease despite CF genetic mutations that portend worse prognosis. This may become more evident as we follow the pediatric CF population into adulthood as some highly effective modulator therapies (HEMT) are approved for those as young as 1 year old. This review will outline the current research and knowledge available in the evolving nutritional health of people with CF as it relates to the impact of HEMT on anthropometrics, body composition, and energy expenditure, exocrine and endocrine pancreatic insufficiencies (the latter resulting in CF-related diabetes), vitamin and mineral deficiencies, and nutritional health in CF as it relates to pregnancy and lung transplantation.

Staphylococcus aureus Small-Colony Variants from Airways of Adult Cystic Fibrosis Patients as Precursors of Adaptive Antibiotic-Resistant Mutations

Prototypic Staphylococcus aureus and their small-colony variants (SCVs) are predominant in cystic fibrosis (CF), but the interdependence of these phenotypes is poorly understood. We characterized S. aureus isolates from adult CF patients over several years. Of 18 S. aureus-positive patients (58%), 13 (72%) were positive for SCVs. Characterization included genotyping, SCCmec types, auxotrophy, biofilm production, antibiotic susceptibilities and tolerance, and resistance acquisition rates. Whole-genome sequencing revealed that several patients were colonized with prototypical and SCV-related clones. Some clonal pairs showed acquisition of aminoglycoside resistance that was not explained by aminoglycoside-modifying enzymes, suggesting a mutation-based process. The characteristics of SCVs that could play a role in resistance acquisition were thus investigated further. For instance, SCV isolates produced more biofilm (p < 0.05) and showed a higher survival rate upon exposure to ciprofloxacin and vancomycin compared to their prototypic associated clones. SCVs also developed spontaneous rifampicin resistance mutations at a higher frequency. Accordingly, a laboratory-derived SCV (ΔhemB) acquired resistance to ciprofloxacin and gentamicin faster than its parent counterpart after serial passages in the presence of sub-inhibitory concentrations of antibiotics. These results suggest a role for SCVs in the establishment of persistent antibiotic-resistant clones in adult CF patients.

Post-approval studies with the CFTR modulators Elexacaftor-Tezacaftor-Ivacaftor

Triple combination therapy with the CFTR modulators elexacaftor (ELX), tezacaftor (TEZ) and ivacaftor (IVA) has been qualified as a game changer in cystic fibrosis (CF). We provide an overview of the body of literature on ELX/TEZ/IVA published between November 2019 and February 2023 after approval by the regulators. Recombinant ELX/TEZ/IVA-bound Phe508del CFTR exhibits a wild type conformation in vitro, but in patient's tissue a CFTR glyoisoform is synthesized that is distinct from the wild type and Phe508del isoforms. ELX/TEZ/IVA therapy improved the quality of life of people with CF in the real-life setting irrespective of their anthropometry and lung function at baseline. ELX/TEZ/IVA improved sinonasal and abdominal disease, lung function and morphology, airway microbiology and the basic defect of impaired epithelial chloride and bicarbonate transport. Pregnancy rates were increasing in women with CF. Side effects of mental status changes deserve particular attention in the future.

Elexacaftor-Tezacaftor-Ivacaftor: A Life-Changing Triple Combination of CFTR Modulator Drugs for Cystic Fibrosis

Cystic fibrosis (CF) is a potentially fatal monogenic disease that causes a progressive multisystemic pathology. Over the last decade, the introduction of CF transmembrane conductance regulator (CFTR) modulator drugs into clinical practice has profoundly modified the lives of many people with CF (PwCF) by targeting the fundamental cause of the disease. These drugs consist of the potentiator ivacaftor (VX-770) and the correctors lumacaftor (VX-809), tezacaftor (VX-661), and elexacaftor (VX-445). In particular, the triple combination of CFTR modulators composed of elexacaftor, tezacaftor, and ivacaftor (ETI) represents a life-changing therapy for the majority of PwCF worldwide. A growing number of clinical studies have demonstrated the safety and efficacy of ETI therapy in both short- and long-term (up to two years of follow-up to date) and its ability to significantly reduce pulmonary and gastrointestinal manifestations, sweat chloride concentration, exocrine pancreatic dysfunction, and infertility/subfertility, among other disease signs and symptoms. Nevertheless, ETI therapy-related adverse effects have also been reported, and close monitoring by a multidisciplinary healthcare team remains vital. This review aims to address and discuss the major therapeutic benefits and adverse effects reported by the clinical use of ETI therapy for PwCF.