Cystic Fibrosis Transmembrane Receptor Research Articles

Cystic fibrosis hepatobiliary involvement: an update on imaging in diagnosis and monitoring.

Analysis of the liver using imaging for persons with cystic fibrosis (CF) continues to evolve as new medical therapies are developed improving and extending life. In the 2010s, therapies targeted at modulating protein folding became available to those with CF. Therapeutic options have continued to expand, now providing both correction of protein folding and stabilization for most gene mutations that code for the CF transmembrane receptor protein (CFTR). Today, approximately 80% of persons with CF are eligible for highly effective modulator therapy. With these advancements, the impact of CF on the liver has become more complex, adding metabolism of CFTR modulators to intrinsic CF hepatobiliary involvement (CFHBI) and adding not previously appreciated vascular changes within the liver due to increased longevity in persons with CF. A combination of serum biomarkers and imaging is needed to add clarity to the diagnosis and monitoring of the severity of liver disease. A substantial portion of persons with CF will develop at least CFHBI and a subset will develop advanced cystic fibrosis-associated liver disease (aCFLD); therefore, diagnosis and monitoring need to begin in childhood. In this review, we cover the use of and need for imaging, including elastography, ultrasound, and magnetic resonance imaging (MRI), in diagnosing and monitoring CFHBI and its associated complications.

Impact of elexacaftor/tezacaftor/ivacaftor CFTR modulator therapy on rates of endoscopic sinus surgery in cystic fibrosis.

Elexacaftor/tezacaftor/ivacaftor (ETI), a combination cystic fibrosis transmembrane receptor (CFTR) modulator, has demonstrated improved pulmonary outcomes in individuals with cystic fibrosis (CF). However, ETI's impact on functional endoscopic sinus surgery (FESS) remains unclear. The TriNetX Analytics Research Network, consisting of 120 million global de-identified electronic medical records, was queried from 2012 to 2023 for subjects with CF who underwent sinus surgery.1 Patients on ETI prior to FESS (n=6,056) were propensity score matched to control individuals with CF not on CFTR modulators (n=37,906) and those on other FDA-approved CFTR modulators (tezacaftor/ivacaftor, lumacaftor/ivacaftor, and ivacaftor) (n=2437) based on relevant factors. The primary outcome was the absolute risk reduction (ARR) of undergoing FESS. Secondary outcomes included ARR of CF-related pulmonary exacerbations and hospital admission from 0 to 6, 6 to 12, and 12 to 24 months following FESS. ETI use demonstrated a significant ARR for FESS when compared to CF patients not on CFTR modulators (2.12%; 95% confidence interval [CI] 1.5-2.75; p-value<0.0001) and those on other CFTR modulators (4.7%; 95% CI 3.54-5.85; p-value<0.0001). No significant differences occurred in secondary outcomes between ETI and non-CFTR modulator groups, except for reduced CF-related pulmonary exacerbations from 0 to 6 months post-FESS. Additionally, a significant reduction in pulmonary exacerbations was observed at all time points and hospital admissions within 6 months following FESS compared to those using other CFTR modulators. In a large dataset, CF patients on ETI demonstrated significantly reduced risk of FESS, pulmonary exacerbations, and hospital admission compared to patients not on CFTR modulators or those on other CFTR modulators, suggesting improved sinonasal disease and overall health status in CF.

Concentration-QTcF Modeling of Icenticaftor from a Randomized, Placebo- and Positive-Controlled Thorough QT Study in Healthy Participants.

Icenticaftor (QBW251) is a potentiator of the cystic fibrosis transmembrane receptor. Based on its mechanism of action, icenticaftor is expected to provide benefits in patients with chronic obstructive pulmonary disease by restoring mucociliary clearance, which would eventually lead to a reduction of bacterial colonization and related inflammatory cascade. A placebo- and positive-controlled, 4-way crossover thorough QT study was conducted in 46 healthy participants with the objective to assess the effect of therapeutic (300mg twice daily for 6 days) and supratherapeutic (750mg twice daily for 6 days) oral doses of icenticaftor on electrocardiogram parameters, including concentration-corrected QT (QTc) analysis. Moxifloxacin (400mg, oral) was used as a positive control. In the concentration-QTc analysis performed on pooled data from Day 1 and Day 6 (steady state), the estimated population slope was shallow and slightly negative: -0.0012ms/ng/mL. The effect on the Fridericia corrected QT (QTcF) interval (∆ΔQTcF) was predicted to be -1.3milliseconds at the icenticaftor 300-mg twice-daily peak concentration (geometric mean was 1094ng/mL) and -5.5milliseconds at the 750-mg twice-daily peak concentration (geometric mean Cmax was 4529ng/mL) indicated a mild shortening effect of icenticaftor on QTcF interval length. The results of the by-time-point analysis indicated least squares placebo corrected mean ∆∆QTcF across time points ranged from -7.9 to 0.1milliseconds at 1 and 24hours after dosing both on Day 6 in the 750-mg dose group compared with -3.7 to 1.6milliseconds at 1.5 and 24 hours after dosing on Day1 in the 300-mg dose group. Assay sensitivity was demonstrated with moxifloxacin. The large accumulation of exposures, especially the 4.3-fold increase in peak plasma concentration observed at the icenticaftor 750-mg twice-daily dosage compared with Icenticaftor 300mg twice daily (2.3-fold) on Day 6 provided a large concentration range (up to 9540ng/mL) to evaluate the effect of icenticaftor on ΔΔQTcF. Based on the concentration-QTc analysis, an effect on ΔΔQTcF exceeding 10milliseconds can be excluded within the full observed ranges of plasma concentrations on icenticaftor, up to approximately 9540ng/mL. Icenticaftor at the studied doses demonstrated a mild shortening in QTcF, which is unlikely to be of clinical relevance in a therapeutic setting.

Time to be blunt: Substance use in cystic fibrosis.

As the population of people with cystic fibrosis (pwCF) continues to age, attention is shifting towards addressing the unique challenges teenagers and adults face, including substance use. Changing attitudes and legality regarding marijuana and cannabidiol (CBD) may influence their use among pwCF, but data on the rate of use, reasons for use, and administration methods are lacking. Investigate marijuana, CBD, e-cigarette, and cigarette usage among pwCF and explore differences in demographics, disease severity, and cystic fibrosis transmembrane receptor (CFTR) modulator use between recent users and nonusers. This cross-sectional study used a one-time electronic survey to assess marijuana, CBD, e-cigarette, and cigarette use in pwCF aged >13 years. Demographic and clinical characteristics were compared between recent users and nonusers. The association between recent substance use and CFTR modulator use was analyzed using logistic regressions. Among 226 participants, 29% used marijuana, 22% used CBD, 27% used e-cigarettes, and 22% used cigarettes in the last 12 months. Users of all substances were more likely to be college-educated or aged 29-39 years than nonusers. E-cigarette users were 2.9 times more likely to use CFTR modulators (95% confidence interval [95% CI]: 0.98-11.00, p = .08) and marijuana users were 2.5 times more likely to use CFTR modulators compared to nonusers, adjusted for confounders. CBD, e-cigarettes, and cigarettes users were more likely to have an abnormal mental health screen compared to nonusers. A high proportion of never-users of marijuana and CBD expressed interest in using. Substance use is more prevalent among pwCF than previously reported and needs to be addressed by healthcare providers.

Glutathione and bicarbonate nanoparticles improve mucociliary transport in cystic fibrosis epithelia.

Cystic fibrosis (CF) airway disease is characterized by thick mucus and impaired mucociliary transport (MCT). Loss of functional cystic fibrosis transmembrane receptor (CFTR) leads to acidification and oxidation of airway surface mucus. Replacing bicarbonate (HCO3 -) topically fails due to rapid reabsorption and neutralization, while the scavenging antioxidant, glutathione sulfhydryl (GSH), is also rapidly degraded. The objective of this study is to investigate GSH/NaHCO3 nanoparticles as novel strategy for CF airway disease. GSH/NaHCO3 poly (lactic-co-glycolic acid) nanoparticles were tested on primary CF (F508del/F508del) epithelial cultures to evaluate dose-release curves, surface pH, toxicity, and MCT indices using micro-optical coherence tomography. In vivo tests were performed in three rabbits to assess safety and toxicity. After 1week of daily injections, histopathology, computed tomography (CT), and blood chemistries were performed and compared to three controls. Fluorescent nanoparticles were injected into a rabbit with maxillary sinusitis and explants visualized with confocal microscopy. Sustained release of GSH and HCO3 - with no cellular toxicity was observed over 2weeks. Apical surface pH gradually increased from 6.54±0.13 (baseline) to 7.07±0.10 (24h) (p<0.001) and 6.87 ± 0.05 at 14 days (p<0.001). MCT, ciliary beat frequency, and periciliary liquid were significantly increased. When injected into the maxillary sinuses of rabbits, there were no changes to histology, CT, or blood chemistries. Nanoparticles penetrated rabbit sinusitis mucus on confocal microscopy. Findings suggest that GSH/NaHCO3 - nanoparticles are a promising treatment option for viscous mucus in CF and other respiratory diseases of mucus obstruction such as chronic rhinosinusitis.

Secretin alleviates biliary and liver injury during late-stage primary biliary cholangitis via restoration of secretory processes.

Primary biliary cholangitis (PBC) is characterised by ductopenia, ductular reaction, impairment of anion exchanger 2 (AE2) and the 'bicarbonate umbrella'. Ductulo-canalicular junction (DCJ) derangement is hypothesised to promote PBC progression. The secretin (Sct)/secretin receptor (SR) axis regulates cystic fibrosis transmembrane receptor (CFTR) and AE2, thus promoting choleresis. We evaluated the role of Sct/SR signalling on biliary secretory processes and subsequent injury in a late-stage PBC mouse model and human samples. At 32 weeks of age, female and male wild-type and dominant-negative transforming growth factor beta receptor II (late-stage PBC model) mice were treated with Sct for 1 or 8 weeks. Bulk RNA-sequencing was performed in isolated cholangiocytes from mouse models. Biliary Sct/SR/CFTR/AE2 expression and bile bicarbonate levels were reduced in late-stage PBC mouse models and human samples. Sct treatment decreased bile duct loss, ductular reaction, inflammation, and fibrosis in late-stage PBC models. Sct reduced hepatic bile acid levels, modified bile acid composition, and restored the DCJ and 'bicarbonate umbrella'. RNA-sequencing identified that Sct promoted mature epithelial marker expression, specifically anterior grade protein 2 (Agr2). Late-stage PBC models and human samples exhibited reduced biliary mucin 1 levels, which were enhanced by Sct treatment. Loss of Sct/SR signalling in late-stage PBC results in a faulty 'bicarbonate umbrella' and reduced Agr2-mediated mucin production. Sct restores cholangiocyte secretory processes and DCJ formation through enhanced mature cholangiocyte phenotypes and bile duct growth. Sct treatment may be beneficial for individuals with late-stage PBC. Secretin (Sct) regulates biliary proliferation and bicarbonate secretion in cholangiocytes via its receptor, SR, and in mouse models and human samples of late-stage primary biliary cholangitis (PBC), the Sct/SR axis is blunted along with loss of the protective 'bicarbonate umbrella'. We found that both short- and long-term Sct treatment ameliorated ductular reaction, immune cell influx, and liver fibrosis in late-stage PBC mouse models. Importantly, Sct treatment promoted bicarbonate and mucin secretion and hepatic bile acid efflux, thus reducing cholestatic and toxic bile acid-associated injury in late-stage PBC mouse models. Our work perpetuates the hypothesis that PBC pathogenesis hinges on secretory defects, and restoration of secretory processes that promote the 'bicarbonate umbrella' may be important for amelioration of PBC-associated damage.

Cystic Fibrosis Patients with F508del/Minimal Function Genotype: Laboratory and Nutritional Evaluations after One Year of Elexacaftor/Tezacaftor/Ivacaftor Treatment.

The last ten years have been characterized by an enormous step forward in the therapy and management of patients with Cystic Fibrosis (CF), thanks to the development and combination of Cystic Fibrosis Transmembrane Receptor (CFTR) correctors and potentiators. Specifically, the last approved triple combination elexacaftor/tezacaftor/ivacaftor has been demonstrated to improve lung function in CF patients with both homozygous Phe508del and Phe508del/minimal function genotypes. Here we have assessed the effect of elexacaftor/tezacaftor/ivacaftor in patients carrying the Phe508del/minimal function genotype (n = 20) after one year of treatments on liver function and nutrient absorption with a focus on lipid metabolism. We show that weight, BMI, and albumin significantly increase, suggesting a positive impact of the treatment on nutrient absorption. Furthermore, cholesterol levels as a biomarker of lipid metabolism increased significantly after one year of treatment. Most importantly, we suggest that these results were not dependent on the diet composition, possibly indicating that the drug improves the hepatic synthesis and secretion of proteins and cholesterol.

Impact of pharmacy services on time to elexacaftor-tezacaftor-ivacaftor initiation.

BACKGROUND: The approval of elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA) expanded highly effective cystic fibrosis transmembrane receptor modulator therapy to approximately 90% of persons aged 12 years and older with cystic fibrosis. Clinical pharmacists and pharmacy technicians played a key role in planning for ELX/TEZ/IVA initiation prior to US Food and Drug Administration approval as well as initiating therapy after approval. OBJECTIVE: To evaluate the impact of pharmacy services on time to ELX/TEZ/IVA initiation. METHODS: A retrospective chart review evaluated 146 patients aged at least 12 years with cystic fibrosis qualifying for ELX/TEZ/IVA at a single health system between October 21, 2019, and April 1, 2020. RESULTS: Patients filling ELX/TEZ/IVA at an integrated health system specialty pharmacy (HSSP) vs an outside specialty pharmacy (SP) started on therapy an average of 10.8 days sooner (10.8 days ± 14.0 vs 21.6 days ± 18.8, respectively; P = 0.006). More patients filling at an HSSP received ELX/TEZ/IVA within 14 days of the prescription being written compared with outside SPs (82.0% vs 41.4%, respectively; P = 0.001). Before ELX/TEZ/IVA initiation, patients were hospitalized for a cystic fibrosis-related complication for an average of 6.26 days (range = 0-183) compared with 1.16 days (range = 0-91) after ELX/TEZ/IVA initiation. Lastly, an estimated $134,810 was saved in hospitalization dollars in the 105 patients that were able to fill ELX/TEZ/IVA at an HSSP by initiating the drug an average of 10.8 days sooner than outside SPs. CONCLUSIONS: The results of this study demonstrate the value of an integrated HSSP model. The ability to fill specialty medications at an integrated HSSP may optimize medication access, control costs, and improve patient outcomes for patients receiving care within a health system. DISCLOSURES: Dr Loucks has accepted payment for reviewing content of Lexicomp through Wolters Kluwer Consulting and for presenting and attending the American Society of Health System Pharmacists (ASHP) Summer Meeting in June 2022. Dr Loucks is also a Workgroup Chair for the ASHP Pharmacist Section of Specialty Pharmacy Practitioners - Section Advisory Group on Outcomes and Value. Dr Simonsen was a participant in the Vertex Pharmaceuticals Advisory Board in April 2019 and accepted payment for travel and expenses. The remaining authors have no conflicts of interest or financial interests to disclose. This work is in part supported by the Statistical Expertise and Network (StatNet) Award of Cystic Fibrosis Foundation.

IL-13-programmed airway tuft cells produce PGE2, which promotes CFTR-dependent mucociliary function.

Chronic type 2 (T2) inflammatory diseases of the respiratory tract are characterized by mucus overproduction and disordered mucociliary function, which are largely attributed to the effects of IL-13 on common epithelial cell types (mucus secretory and ciliated cells). The role of rare cells in airway T2 inflammation is less clear, though tuft cells have been shown to be critical in the initiation of T2 immunity in the intestine. Using bulk and single-cell RNA sequencing of airway epithelium and mouse modeling, we found that IL-13 expanded and programmed airway tuft cells toward eicosanoid metabolism and that tuft cell deficiency led to a reduction in airway prostaglandin E2 (PGE2) concentration. Allergic airway epithelia bore a signature of PGE2 activation, and PGE2 activation led to cystic fibrosis transmembrane receptor–dependent ion and fluid secretion and accelerated mucociliary transport. These data reveal a role for tuft cells in regulating epithelial mucociliary function in the allergic airway.

The Effect of CFTR Modulators on Airway Infection in Cystic Fibrosis.

The advent of Cystic fibrosis transmembrane receptor (CFTR) modulators in 2012 was a critical event in the history of cystic fibrosis (CF) treatment. Unlike traditional therapies that target downstream effects of CFTR dysfunction, CFTR modulators aim to correct the underlying defect at the protein level. These genotype-specific therapies are now available for an increasing number of CF patients, transforming the way we view the condition from a life-limiting disease to one that can be effectively managed. Several studies have demonstrated the vast improvement CFTR modulators have on normalization of sweat chloride, CFTR function, clinical endpoints, and frequency of pulmonary exacerbation. However, their impact on other aspects of the disease, such as pathogenic burden and airway infection, remain under explored. Frequent airway infections as a result of increased susceptibility and impaired innate immune response are a serious problem within CF, often leading to accelerated decline in lung function and disease progression. Current evidence suggests that CFTR modulators are unable to eradicate pathogenic organisms in those with already established lung disease. However, this may not be the case for those with relatively low levels of disease progression and conserved microbial diversity, such as young patients. Furthermore, it remains unknown whether the restorative effects exerted by CFTR modulators extend to immune cells, such as phagocytes, which have the potential to modulate the response of people with CF (pwCF) to infection. Throughout this review, we look at the potential impact of CFTR modulators on airway infection in CF and their ability to shape impaired pulmonary defences to pathogens.

Cystic Fibrosis: New Insights into Therapeutic Approaches

Since the identification of Cystic Fibrosis (CF) as a disease in 1938 until 2012, only therapies to treat symptoms rather than etiological therapies have been used to treat the disease. Over the last few years, new technologies have been developed, and gene editing strategies are now moving toward a one-time cure. This review will summarize recent advances in etiological therapies that target the basic defect in the CF Transmembrane Receptor (CFTR), the protein that is mutated in CF. We will discuss how newly identified compounds can directly target mutated CFTR to improve its function. Moreover, we will discuss how proteostasis regulators can modify the environment in which the mutant CFTR protein is synthesized and decayed, thus restoring CFTR function. The future of CF therapies lies in combinatory therapies that may be personalized for each CF patient.

The demographics of adverse outcomes in cystic fibrosis

Understanding variability in cystic fibrosis (CF) health outcomes requires an understanding of factors that go far beyond Cystic Fibrosis Transmembrane Receptor (CFTR) function caused by different gene mutations. Social and environmental factors that influence health have a significant influence on the trajectory of health in CF and in other chronic diseases. In this article, we review demographic factors associated with poorer health outcomes in CF, known and postulated biological mechanisms of these outcomes, and interventions that healthcare teams can implement that may reduce outcome disparities.

Secondhand Smoke Exposure and Serum Trypsinogen in Cystic Fibrosis Carriers.

The objective of this study was to determine if infants carrying 1 cystic fibrosis transmembrane receptor (CFTR) mutation demonstrate pancreatic inflammation in response to tobacco exposure. Cystic fibrosis carrier infants aged 4 to 16 weeks were prospectively enrolled. Tobacco exposure was assessed by survey and maternal hair nicotine analysis. Serum immunoreactive trypsinogen (IRT) levels at birth and at the time of recruitment were analyzed relative to the presence or absence of tobacco exposure. The effect of the severity of the CFTR mutation carried by the infant on the tobacco-IRT relationship was also analyzed. Forty-eight infants completed the study. Newborn screen and follow-up IRT levels were not different between exposed infants (19 by hair analysis) and nonexposed infants (29 by hair analysis). Follow-up IRT levels were lower in infants with more severe CFTR mutations (P = 0.005). There was no difference in follow-up IRT based on CFTR mutation severity in exposed infants. Nonexposed infants with milder CFTR mutations had higher median IRT values on follow-up testing than those with more severe CFTR mutations (P < 0.05). The pancreas of cystic fibrosis carrier infants is affected by tobacco exposure, and those carrying less severe CFTR mutations may be more susceptible to tobacco effects.

Acquired cystic fibrosis transmembrane conductance regulator protein (CFTR) dysfunction and cigarette smoking

Cystic fibrosis (CF) remains a prevalent genetically inherited disease in Caucasianpopulations. Investigation of the respiratory symptoms which occur in patients with CF helps usunderstand the pathophysiology of chronic lung disease. Environmental insults, such as cigarettesmoke, can reduce the cystic fibrosis transmembrane receptor (CFTR) function or expressionleading to an acquired CF phenotype and could contribute to the development and progressionof smoking-related lung disease. However, it is uncertain if the acquired CF phenotype can bediagnosed with the same methods, such as the sweat chloride test and the measurementof nasal potential difference, used for genetically-acquired CF. More studies are needed toinvestigate the prevalence of acquired CFTR dysfunction and the differences between acquiredand genetically-inherited CFTR dysfunction. Overall, acquired CFTR dysfunction challengesthe distinction between genetic and acquired disorders, suggesting that environmental agentsmay modulate the functions of genes and the increase risk for pulmonary disease.

Effect of Cystic Fibrosis Transmembrane Receptor Modulators on Anthropometric and Growth Parameters in Individuals with Cystic Fibrosis: A Systematic Review (OR36-08-19)

ObjectivesIndividuals with cystic fibrosis (CF) are at high risk for malnutrition and poor growth. New drugs that modulate CF transmembrane receptor (CFTR) function are available, although their effects on anthropometric parameters are not clear. This systematic review aimed to determine if various CFTR modulator therapies affect weight and growth parameters in individuals with CF. MethodsA literature search was conducted using MEDLINE, CINAHL and Embase databases for peer-reviewed, randomized controlled trials (RCT) published from January 2002 to May 2018 that examined the effect of CFTR modulation therapy on weight and growth parameters in children and adults with CF. Articles were screened for relevance, data was extracted and summarized, and risk of bias was assessed to determine the quality of evidence. ResultsA total of 612 original articles were identified, and 13 articles representing 10 RCTs were included in qualitative synthesis and three were included in quantitative synthesis. All but one RCT demonstrated low risk of bias. The targeted class of CFTR mutation varied by RCT. Studies indicated that, in children and adults with CF with class III mutations, ivacaftor treatment alone increased weight and BMI (4 RCTs), but it did not influence growth in individuals with class II (1 RCT) or class IV mutations (1 RCT). Treatment with ivacaftor + lumacaftor in adults homozygous for the F508del CFTR mutation (class II) increased BMI following 24 weeks of treatment (2 RCTs), but there was no effect in adults heterozygous for the mutation treated for 8 weeks (1 RCT). Treatment with lumacaftor + tezacaftor in individuals ages 12–20 years with class II mutations did not change growth parameters (1 RCT). ConclusionsEffects of CFTR modulators on increasing weight and growth in individuals with CF are likely dependent on the therapy formulation (single vs combination therapy) and the targeted CFTR mutation. Whereas ivacaftor alone increases weight and growth parameters in individuals with class III mutations, ivacaftor + lumacaftor is more effective at increasing BMI in adults homozygous for the class II F508del CFTR mutation. Additional studies are needed to determine effects of other CFTR modulator drugs on growth parameters in individuals with varying CFTR mutations. Funding SourcesAcademy of Nutrition and Dietetics/Medical Nutrition DPG, National Institutes of Health.

Inhalation treatment of cystic fibrosis with lumacaftor and ivacaftor co-delivered by nanostructured lipid carriers

Cystic fibrosis (CF), a most deadly genetic disorder, is caused by mutations of CF transmembrane receptor (CFTR) - a chloride channel present at the surface of epithelial cells. In general, two steps have to be involved in treatment of the disease: correction of cellular defects and potentiation to further increase channel opening. Consequently, a combinatorial simultaneous treatment with two drugs with different mechanisms of action, lumacaftor and ivacaftor, has been recently proposed. While lumacaftor is used to correct p.Phe508del mutation (the loss of phenylalanine at position 508) and increase the amount of cell surface–localized CFTR protein, ivacaftor serves as a CFTR potentiator that increases the open probability of CFTR channels. Since the main organ that is affected by cystic fibrosis is the lung, the delivery of drugs directly to the lungs by inhalation has a potential to enhance the efficacy of the treatment of CF and limit adverse side effects upon healthy tissues and organs. Based on our extensive experience in inhalation delivering of drugs by different nanocarriers, we selected nanostructured lipid carriers (NLC) for the delivery both drugs directly to the lungs by inhalation and tested NLC loaded with drugs in vitro (normal and CF human bronchial epithelial cells) and in vivo (homozygote/homozygote bi-transgenic mice with CF). The results show that the designed NLCs demonstrated a high drug loading efficiency and were internalized in the cytoplasm of CF cells. It was found that NLC-loaded drugs were able to restore the expression and function of CFTR protein. As a result, the combination of lumacaftor and ivacaftor delivered by lipid nanoparticles directly into the lungs was highly effective in treating lung manifestations of cystic fibrosis.

Non-coding RNA in cystic fibrosis

Non-coding RNAs (ncRNAs) are an abundant class of RNAs that include small ncRNAs, long non-coding RNAs (lncRNA) and pseudogenes. The human ncRNA atlas includes thousands of these specialised RNA molecules that are further subcategorised based on their size or function. Two of the more well-known and widely studied ncRNA species are microRNAs (miRNAs) and lncRNAs. These are regulatory RNAs and their altered expression has been implicated in the pathogenesis of a variety of human diseases. Failure to express a functional cystic fibrosis (CF) transmembrane receptor (CFTR) chloride ion channel in epithelial cells underpins CF. Secondary to the CFTR defect, it is known that other pathways can be altered and these may contribute to the pathophysiology of CF lung disease in particular. For example, quantitative alterations in expression of some ncRNAs are associated with CF. In recent years, there has been a series of published studies exploring ncRNA expression and function in CF. The majority have focussed principally on miRNAs, with just a handful of reports to date on lncRNAs. The present study reviews what is currently known about ncRNA expression and function in CF, and discusses the possibility of applying this knowledge to the clinical management of CF in the near future.

Next-generation sequencing for identifying genetic mutations in adults with bronchiectasis.

Defective airway host-defense (e.g., altered mucus properties, ciliary defects) contributes to the pathogenesis of bronchiectasis. This study aims to determine whether genetic mutations associated with defective airway host-defense are implicated in the pathogenesis of bronchiectasis. Based on the systematic screening of 32 frequently reported bronchiectasis-associated genes, we performed next-generation sequencing (NGS) on peripheral blood samples from 192 bronchiectasis patients and 100 healthy subjects. The variant distribution frequency and pathogenicity of mutations were analyzed. We identified 162 rare variants in 192 bronchiectasis patients, and 85 rare variants among 100 healthy subjects. Among bronchiectasis patients, 25 (15.4%), 117 (72.2%) and 18 (11.1%) rare variants were associated with cystic fibrosis transmembrane receptor (CFTR), epithelial sodium channel, and primary ciliary dyskinesia genes, respectively. Biallelic CFTR variants were detected in four bronchiectasis patients but none of the healthy subjects. Carriers of homozygous p.M470 plus at least one CFTR rare variant were detected in 6.3% of bronchiectasis patients (n=12) and in 1.0% of healthy subjects (n=1, P=0.039). Twenty-six patients (16 with idiopathic and 6 with post-infectious bronchiectasis) harbored biallelic variants. Bronchiectasis patients with biallelic DNAH5 variants, or biallelic CFTR variants plus an epithelial sodium channel variant, tended to have greater disease severity. Genetic mutations leading to impaired host-defense might have implicated in the pathogenesis of bronchiectasis. Genetic screening may be a useful tool for unraveling the underlying causes of bronchiectasis, and offers molecular information which is complementary to conventional etiologic assessment for bronchiectasis.

Pancreatitis and pancreatic cystosis in Cystic Fibrosis

The pathologic effects of an altered cystic fibrosis transmembrane receptor (CFTR) protein on the exocrine pancreas is ubiquitous and of varying severity. In this section, pancreatitis and pancreatic cystosis are covered.

Differentiation of human bronchial epithelial cells: role of hydrocortisone in development of ion transport pathways involved in mucociliary clearance.

Glucocorticoids strongly influence the mucosal-defense functions performed by the bronchial epithelium, and inhaled corticosteroids are critical in the treatment of patients with inflammatory airway diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis. A common pathology associated with these diseases is reduced mucociliary clearance, a defense mechanism involving the coordinated transport of salt, water, and mucus by the bronchial epithelium, ultimately leading to retention of pathogens and particles in the airways and to further disease progression. In the present study we investigated the role of hydrocortisone (HC) in differentiation and development of the ion transport phenotype of normal human bronchial epithelial cells under air-liquid interface conditions. Normal human bronchial epithelial cells differentiated in the absence of HC (HC0) showed significantly less benzamil-sensitive short-circuit current than controls, as well as a reduced response after stimulation with the selective β2-adrenergic receptor agonist salbutamol. Apical membrane localization of epithelial Na(+) channel α-subunits was similarly reduced in HC0 cells compared with controls, supporting a role of HC in the trafficking and density of Na(+) channels in the plasma membrane. Additionally, glucocorticoid exposure during differentiation regulated the transcription of cystic fibrosis transmembrane conductance regulator and β2-adrenergic receptor mRNAs and appeared to be necessary for the expression of cystic fibrosis transmembrane conductance regulator-dependent anion secretion in response to β2-agonists. HC had no significant effect on surface cell differentiation but did modulate the expression of mucin mRNAs. These findings indicate that glucocorticoids support mucosal defense by regulating critical transport pathways essential for effective mucociliary clearance.