Fibrosis Transmembrane Conductance Regulator Gene Research Articles

Transcriptional analysis of cystic fibrosis airways at single-cell resolution reveals altered epithelial cell states and composition.

Cystic fibrosis (CF) is a lethal autosomal recessive disorder that afflicts more than 70,000 people. People with CF experience multi-organ dysfunction resulting from aberrant electrolyte transport across polarized epithelia due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF-related lung disease is by far the most important determinant of morbidity and mortality. Here we report results from a multi-institute consortium in which single-cell transcriptomics were applied to define disease-related changes by comparing the proximal airway of CF donors (n = 19) undergoing transplantation for end-stage lung disease with that of previously healthy lung donors (n = 19). Disease-dependent differences observed include an overabundance of epithelial cells transitioning to specialized ciliated and secretory cell subsets coupled with an unexpected decrease in cycling basal cells. Our study yields a molecular atlas of the proximal airway epithelium that will provide insights for the development of new targeted therapies for CF airway disease.

Effect of Alpha-1 Antitrypsin on CFTR Levels in Primary Human Airway Epithelial Cells Grown at the Air-Liquid-Interface.

The cystic fibrosis transmembrane conductance regulator (CFTR) gene is influenced by the fundamental cellular processes like epithelial differentiation/polarization, regeneration and epithelial–mesenchymal transition. Defects in CFTR protein levels and/or function lead to decreased airway surface liquid layer facilitating microbial colonization and inflammation. The SERPINA1 gene, encoding alpha1-antitrypsin (AAT) protein, is one of the genes implicated in CF, however it remains unknown whether AAT has any influence on CFTR levels. In this study we assessed CFTR protein levels in primary human lung epithelial cells grown at the air-liquid-interface (ALI) alone or pre-incubated with AAT by Western blots and immunohistochemistry. Histological analysis of ALI inserts revealed CFTR- and AAT-positive cells but no AAT-CFTR co-localization. When 0.5 mg/mL of AAT was added to apical or basolateral compartments of pro-inflammatory activated ALI cultures, CFTR levels increased relative to activated ALIs. This finding suggests that AAT is CFTR-modulating protein, albeit its effects may depend on the concentration and the route of administration. Human lung epithelial ALI cultures provide a useful tool for studies in detail how AAT or other pharmaceuticals affect the levels and activity of CFTR.

Hereditary pancreatitis in childhood: course of disease and complications

Hereditary pancreatitis is rare. Pain therapy for juvenile symptom onset, child development and the risk of pancreatic carcinoma in adulthood must be considered. Data from acohort of 11 patients with disease onset in childhood (< 16years) were analyzed retrospectively. The gene encoding cationic trypsinogen (PRSS1), serine protease inhibitor Kazal type1 (SPINK1) and cystic fibrosis transmembrane conductance regulator (CFTR) genes were investigated as genetic factors. Treatment concept and complications were registered. Prognosis, treatment success and quality of life were objectified using the chronic pancreatitis prognosis score and astandardized questionnaire (KIDSCREEN-10 index). The mean age of symptom onset was 7.5 ±4.2years. The PRSS1 and SPINK1 mutations each occurred with 36.4%, 3 patients had apancreas divisum and 2 along common channel. The course of pancreatitis was obstructive in 90.9%. Exocrine pancreatic insufficiency occurred in seven patients so far (mean age 12.5years). Stenting was performed in 72.7% and 18.2% needed pancreatic surgery. Currently the chronic prognosis score is on average 7.5points, pain on numerical rating scale0 (no pain). The mean KIDSCREEN‑T score of 66.9 confirms avery good quality of life. Patients with genetically caused chronic pancreatitis are rare. Their care ranges from pain therapy in childhood and adolescence to questions concerning family planning and pancreatic cancer prevention from mid-adulthood onward. The disease is challenging for the interdisciplinary cooperation. We found the step-up strategy to be agood option for pain therapy. Anational registry monitored by scientific societies with active recruitment for screening examinations will further improve and ensure care in the long term.

On the Corner of Models and Cure: Gene Editing in Cystic Fibrosis.

Cystic fibrosis (CF) is a severe genetic disease for which curative treatment is still lacking. Next generation biotechnologies and more efficient cell-based and in vivo disease models are accelerating the development of novel therapies for CF. Gene editing tools, like CRISPR-based systems, can be used to make targeted modifications in the genome, allowing to correct mutations directly in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. Alternatively, with these tools more relevant disease models can be generated, which in turn will be invaluable to evaluate novel gene editing-based therapies for CF. This critical review offers a comprehensive description of currently available tools for genome editing, and the cell and animal models which are available to evaluate them. Next, we will give an extensive overview of proof-of-concept applications of gene editing in the field of CF. Finally, we will touch upon the challenges that need to be addressed before these proof-of-concept studies can be translated towards a therapy for people with CF.

A survey of the prevalence, management and outcome of infants with an inconclusive diagnosis following newborn bloodspot screening for cystic fibrosis (CRMS/CFSPID) in six Italian centres

ObjectiveWe evaluated the prevalence, Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene profile, clinical data, management and outcome for infants with a CFTR-related metabolic syndrome/CF Screen Positive, Inconclusive Diagnosis (CRMS/CFSPID) designation from six Italian centres. MethodsAll newborn bloodspot screening (NBS) positive infants born from January 2011 to August 2018 with a CF diagnosis or a CRMS/CFSPID designation were enrolled. Data on sweat testing, genetics, clinical course and management were collected. ResultsWe enrolled 257 CF patientsand 336 infants with a CRMS/CFSPID designation (CF: CRMS/CFSPID ratio of 1:1.30).Blood immuno-reactive trypsinogen (IRT) was significantly lower in CRMS/CFSPID infants and the F508del variant accounted for only 20% of alleles. Children with CRMS/CFSPID showed a milder clinical course, pancreatic sufficiency compared to CF infants. Varied practice across centres was identified regarding sweat testing, chest radiograph (8-100%) and salt supplementation (11-90%). Eighteen (5.3%) CRMS/CFSPID infants converted or were reclassified to diagnosis of CF. Four infants (1.3%) developed a clinical feature consistent with a CFTR-related disorder (1.2%). Twenty-seven were re-classified as healthy carriers (8.0%) and 16 as healthy infants (4.8%). ConclusionsWe have identified considerable variability in the evaluation and management of infants with an inconclusive diagnosis following NBS across six Italian centres. CRMS/CFSPID is more regularly seen in this population compared to countries with higher prevalence of F508del.Conversion to a CF diagnosis was recorded in 18 (5.3%) of CRMS/CFSPID infants and in 16 was as a result of increasing sweat chloride concentration.

Diagnostic tools and CFTR functional assays in cystic fibrosis: utility and availability in Switzerland.

Cystic fibrosis (CF) is a genetic disease caused by a bi-allelic mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. When the diagnosis cannot be confirmed by a positive sweat test or/and the identification of two CF-causing variants, international guidelines recommend the use of CFTR functional assays. These tests assess whether CFTR activity is normal or diminished/absent through measurement of CFTR-mediated chloride secretion/absorption. CFTR functional assays are not only useful for diagnostic purposes but can also serve as a surrogate outcome for clinical trials of CFTR modulators, which are emerging therapeutic agents designed to correct the malfunctioning protein. In the near future they could also be used as precision-medicine techniques, to help guidance and optimisation of treatment. Until now, sweat testing has been the only CFTR functional assay available in Switzerland. Since 2020, the Centre Hospitalier Universitaire Vaudois (CHUV) at Lausanne and the Lucerne Children&rsquo;s Hospital perform nasal potential difference measurement. Moreover, The Ecole Polytechnique F&eacute;d&eacute;rale de Lausanne (EPFL) established a reliable procedure to generate adult intestinal organoids, i.e., stem cell-derived in-vitro grown mini tissues, extracted from rectal biopsies, which can be used to assess CFTR function in vitro. This narrative review describes the most popular CFTR functional assays, as well as their indications, limitations and availability in Switzerland.

Cystic Fibrosis Lung Disease Modifiers and Their Relevance in the New Era of Precision Medicine.

Our understanding of cystic fibrosis (CF) has grown exponentially since the discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 1989. With evolving genetic and genomic tools, we have come to better understand the role of CFTR genotypes in the pathophysiology of the disease. This, in turn, has paved the way for the development of modulator therapies targeted at mutations in the CFTR, which are arguably one of the greatest advances in the treatment of CF. These modulator therapies, however, do not target all the mutations in CFTR that are seen in patients with CF and, furthermore, a variation in response is seen in patients with the same genotype who are taking modulator therapies. There is growing evidence to support the role of non-CFTR modifiers, both genetic and environmental, in determining the variation seen in CF morbidity and mortality and also in the response to existing therapies. This review focusses on key findings from studies using candidate gene and genome-wide approaches to identify CF modifier genes of lung disease in cystic fibrosis and considers the interaction between modifiers and the response to modulator therapies. As the use of modulator therapies expands and we gain data around outcomes, it will be of great interest to investigate this interaction further. Going forward, it will also be crucial to better understand the relative influence of genomic versus environmental factors. With this understanding, we can truly begin to deliver personalised care by better profiling the likely disease phenotype for each patient and their response to treatment.

The Future of CRISPR: Looking at Gene Editing as a Treatment For Cystic Fibrosis

Cystic Fibrosis (CF) is a genetically inherited chronic disease that causes the production of a thick and sticky mucus primarily in the lungs. The condition tends to become worse over time. Clogged lungs and other internal organs result in breathing issues, susceptibility to infections, digestive problems, and lack of nutrition. CF is an autosomal recessive disease, indicating that an individual must inherit two copies of the defective Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene, which then encodes for a malfunctioning CFTR protein. Because of the large number of CF patients that cannot be treated with these CFTR modulators, using gene editing to directly target the mutation can be more effective and efficient in treating cystic fibrosis. In this paper, we will discuss the promises and limitations for using gene editing as a treatment for CF.

Cystic fibrosis: current treatment and future direction

Cystic fibrosis is an autosomal recessive genetic disorder, characterized by mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, leading to abnormality in the chloride channels of the mucus and sweat producing glands. Multiple organs systems are affected in this disorder, like respiratory system and gastrointestinal tract, severely impacting the patient’s quality of life, eventually leading on to several complications and death. Since the uncovering of the underlying genetic defect in cystic fibrosis (CF), our knowledge of the disease process has increased substantially, but we still lack a holistic approach to its management, which comprises of multiple facades, requiring both pharmacological and non-pharmacological or rehabilitatory approaches. So far, the therapeutic options were limited to targeting the consequences and complications of the disease, such as respiratory infection, mucus retention, pancreatic insufficiency, etc., but now several promising therapies may be able to address the underlying pathology rather than its long-term effects. This review summarizes the current and upcoming pharmacological options for CF, such as those targeting the CFTR gene defect directly, including gene editing, CFTR correctors and potentiators; drugs targeting the epithelial sodium channels (ENaC inhibitors); repositioning of some existing drugs and evaluating their role in CF; and understanding the disease better by transcriptomic approaches and the role of gut microbiota in the disease process and severity.

CFTR Modulator Therapy with Lumacaftor/Ivacaftor Alters Plasma Concentrations of Lipid-Soluble Vitamins A and E in Patients with Cystic Fibrosis.

Rationale: Cystic fibrosis (CF), caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, leads to impaired pancreatic function and therefore reduced intestinal absorption of lipids and fat-soluble vitamins especially in patients with CF developing pancreatic insufficiency (PI). Previous studies showed that CFTR modulator therapy with lumacaftor-ivacaftor (LUM/IVA) in Phe508del-homozygous patients with CF results in improvement of pulmonary disease and thriving. However, the effects of LUM/IVA on plasma concentration of the lipid soluble vitamins A and E remain unknown. Objectives: To investigate the course of plasma vitamin A and E in patients with CF under LUM/IVA therapy. Methods: Data from annual follow-up examinations of patients with CF were obtained to assess clinical outcomes including pulmonary function status, body mass index (BMI), and clinical chemistry as well as fat-soluble vitamins in Phe508del-homozygous CF patients before initiation and during LUM/IVA therapy. Results: Patients with CF receiving LUM/IVA improved substantially, including improvement in pulmonary inflammation, associated with a decrease in blood immunoglobulin G (IgG) from 9.4 to 8.2 g/L after two years (p < 0.001). During the same time, plasma vitamin A increased significantly from 1.2 to 1.6 µmol/L (p < 0.05), however, levels above the upper limit of normal were not detected in any of the patients. In contrast, plasma vitamin E as vitamin E/cholesterol ratio decreased moderately over the same time from 6.2 to 5.5 µmol/L (p < 0.01). Conclusions: CFTR modulator therapy with LUM/IVA alters concentrations of vitamins A and vitamin E in plasma. The increase of vitamin A must be monitored critically to avoid hypervitaminosis A in patients with CF.

Update on Calcium Signaling in Cystic Fibrosis Lung Disease

Cystic fibrosis (CF) is an autosomal recessive disorder characterized by mutations in the cystic fibrosis transmembrane conductance regulator gene, which causes multifunctional defects that preferentially affect the airways. Abnormal viscosity of mucus secretions, persistent pathogen infections, hyperinflammation, and lung tissue damage compose the classical pathological manifestation referred to as CF lung disease. Among the multifunctional defects associated with defective CFTR, increasing evidence supports the relevant role of perturbed calcium (Ca2+) signaling in the pathophysiology of CF lung disease. The Ca2+ ion is a critical player in cell functioning and survival. Its intracellular homeostasis is maintained by a fine balance between channels, transporters, and exchangers, mediating the influx and efflux of the ion across the plasma membrane and the intracellular organelles. An abnormal Ca2+ profile has been observed in CF cells, including airway epithelial and immune cells, with heavy repercussions on cell function, viability, and susceptibility to pathogens, contributing to proinflammatory overstimulation, organelle dysfunction, oxidative stress, and excessive cytokines release in CF lung. This review discusses the role of Ca2+ signaling in CF and how its dysregulation in airway epithelial and immune cells contributes to hyperinflammation in the CF lung. Finally, we provide an outlook on the therapeutic options that target the Ca2+ signaling to treat the CF lung disease.

Pancreatitis severity in mice with impaired CFTR function but pancreatic sufficiency is mediated via ductal and inflammatory cells-Not acinar cells.

Mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR) are an established risk factor for cystic fibrosis (CF) and chronic pancreatitis. Whereas patients with CF usually develop complete exocrine pancreatic insufficiency, pancreatitis patients with CFTR mutations have mostly preserved exocrine pancreatic function. We therefore used a strain of transgenic mice with significant residual CFTR function (CFTRtm1HGU) to induce pancreatitis experimentally by serial caerulein injections. Protease activation and necrosis were investigated in isolated acini, disease severity over 24h, pancreatic function by MRI, isolated duct stimulation and faecal chymotrypsin, and leucocyte function by ex vivo lipopolysaccharide (LPS) stimulation. Pancreatic and lung injury were more severe in CFTRtm1HGU but intrapancreatic trypsin and serum enzyme activities higher than in wild‐type controls only at 8h, a time interval previously attributed to leucocyte infiltration. CCK‐induced trypsin activation and necrosis in acini from CFTRtm1HGU did not differ from controls. Fluid and bicarbonate secretion were greatly impaired, whereas faecal chymotrypsin remained unchanged. LPS stimulation of splenocytes from CFTRtm1HGU resulted in increased INF‐γ and IL‐6, but decreased IL‐10 secretion. CFTR mutations that preserve residual pancreatic function significantly increase the severity of experimental pancreatitis—mostly via impairing duct cell function and a shift towards a pro‐inflammatory phenotype, not by rendering acinar cells more susceptible to pathological stimuli.

Colorectal Cancer in People with Cystic Fibrosis under the Age of 40: A Case Series

Introduction Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF), a disease which affects primarily the respiratory and gastrointestinal (GI) tracts. The lifetime risk of colorectal cancer (CRC) in patients with CF is approximately 5-10 times that of the general population. In 2018, the CF Foundation CRC Screening Task Force recommended initiating CRC screening in adults with CF at age 40. Case Presentations In this case series, we present three cases of females with CF younger than age 40 diagnosed with CRC with variable presentations and stages. We discuss the data supporting current CRC screening guidelines in CF in an effort to raise awareness among clinicians regarding young-onset CRC in this population. Furthermore, we aim for this case series to help drive further investigation into the mechanisms underlying CF-related CRC and to open the door to changes in current screening practices. Conclusion People with CF are at substantially higher risk of development of CRC relative to the general population. While current CRC screening practices advocate for earlier screening in this population compared to average-risk patients, this case series highlights potential limitations to current screening guidelines.

Ten cases of aquagenic syringeal acrokeratoderma revealed during the COVID‐19 outbreak

Aquagenic syringeal acrokeratoderma (ASA) is a rare, acquired disease affecting predominantly young women. It is characterised by the development of hypopigmented, translucent, flat-topped, oedematous papules and plaques that form hyperwrinkling or keratoderma.1 It occurs after 3-5 minutes of contact with water and resolves when the hand dries.1 Although its aetiology is not known exactly, it has been suggested that the disease may develop due to genetic predisposition or diseases such as cystic fibrosis, focal hyperhidrosis and Raynaud's phenomenon.2, 3 However, increased personal hygiene measures such as wearing personal protective equipment, excessive hand washing and disinfection in the COVID-19 epidemic may play a role in the aetiology of ASA.5 Here we present ten cases with a very short history of ASA where lesions were first seen after the COVID-19 outbreak. The ages of the patients varied between 5 and 24 years (6 female, 4 male). The duration of disease was between 20 days and 2 months. Lesions of all patients were occurred by continuous water contact for 5 minutes. Cystic fibrosis transmembrane conductance regulator (CFTR) gene test could not be performed due to technical difficulties. The disease was diagnosed clinically. Two patients had atopic dermatitis and one patient had a history of hyperhidrosis. Parents of 60% of the patients were working in the health sector. Case 7 and 8 were siblings, although they lived in separate cities, the lesions occurred at approximately the same time. Also, the case 9 and 10 were siblings and lesions occurred at the same time. All lesions were localised in the palmar regions of the hands (Figure 1). Seventy percentage of the patients was washing their hands frequently for hygiene. The patients had no previous history of ASA and the first lesions of all patients appeared during the COVID-19 pandemic. The lesions of 70 percent of the patients were left untreated, and the lesions largely disappeared with the reduction of water contact. One patient was cured with a mixture of glycerin, petrolatum, salicylic acid, mometasone furoate, vitamin E and Centella asiatica. One patient was unresponsive to aluminium chloride therapy. The clinical and demographic data of the patients are shown in Table 1. In the pathogenesis of aquagenic syringeal acrokeratoderma, the increase in the water-binding capacity of epidermal keratinocytes due to the increase in epidermal sodium concentration has been accused.2 The aetiology of the disease is not fully known. However, in the COVID-19 pandemic, hygiene practices are carried out excessively. According to a recently published case reports, it was evaluated that ASA was formed as a result of excessive and prolonged water contact during the COVID-19 pandemic.4, 5 Due to the COVID-19 epidemic, 70 percent of our patients was washing their hands frequently and were in frequent contact with the disinfectant. In addition, it was thought that the fact that at least one of the parents of 70% of the cases was a healthcare worker, strict hygiene measures were followed and this could lead to the development of ASA. Most cases are sporadic and acquired, but familial cases with significant female dominance have also been reported..6 The fact that there are three siblings (6 patients in total) among our cases shows that ASA also has a genetic tendency. Treatment options include topical aluminium chloride, glycerol, salicylic acid, urea and ammonium lactate creams, iontophoresis and botulinum toxin.4 The vast majority of our cases were left untreated, and their lesions largely regressed with the reduction in water contact. As a result, although there are discussions on the pathophysiology of ASA, we think that the implementation of long-term and strict hygiene rules in the COVID-19 epidemic contributes to the emergence of ASA. In addition, the fact that 60% of the cases are siblings suggests that the disease has a genetic predisposition. The authors have declared no conflicts of interest for this article. Not applicable. Erhan Ayhan. No data are available.

CFTR Deficiency Affects Glucose Homeostasis via Regulating GLUT4 Plasma Membrane Transportation.

Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. CF-related diabetes (CFRD) is one of the most prevalent comorbidities of CF. Altered glucose homeostasis has been reported in CF patients. The mechanism has not been fully elucidated. Besides the consequence of pancreatic endocrine dysfunction, we focus on insulin-responsive tissues and glucose transportation to explain glucose homeostasis alteration in CFRD. Herein, we found that CFTR knockout mice exhibited insulin resistance and glucose tolerance. Furthermore, we demonstrated insulin-induced glucose transporter 4 (GLUT4) translocation to the cell membrane was abnormal in the CFTR knockout mice muscle fibers, suggesting that defective intracellular GLUT4 transportation may be the cause of impaired insulin responses and glucose homeostasis. We further demonstrated that PI(4,5)P2 could rescue CFTR related defective intracellular GLUT4 transportation, and CFTR could regulate PI(4,5)P2 cellular level through PIP5KA, suggesting PI(4,5)P2 is a down-stream signal of CFTR. Our results revealed a new signal mechanism of CFTR in GLUT4 translocation regulation, which helps explain glucose homeostasis alteration in CF patients.

Current Status of Genetic Diagnosis Laboratories and Frequency of Genetic Variants Associated with Cystic Fibrosis through a Newborn-Screening Program in Turkey

Background: Cystic fibrosis (CF) is the most common worldwide, life-shortening multisystem hereditary disease, with an autosomal recessive inheritance pattern caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The national newborn screening (NBS) program for CF has been initiated in Turkey since 2015. If the immunoreactive trypsinogen (IRT) is elevated (higher than 70 μg/L in the second control) and confirmed by sweat test or clinical findings, genetic testing is performed. The aims of this study are to emphasize the effect of NBS on the status of genetic diagnosis centers with the increasing numbers of molecular testing methods, and to determine the numbers and types of CFTR mutations in Turkey. Methods: The next-generation sequencing (NGS) and multiplex ligation-dependent probe amplification (MLPA) results of 1595 newborns, who were referred to Cukurova University Adana Genetic Diseases Diagnosis and Treatment Center (AGENTEM) for molecular genetic testing, were evaluated with positive CF NBS program results since 2017. Results: According to the results; 560 (35.1%) of the 1595 patients carried at least 1 (one) CF-related variant, while 1035 patients (64.9%) had no mutation. Compound heterozygosity for two mutations was the most common in patients, while two detected variants were homozygote in 14 patients. A total of 161 variants were detected in 561 patients with mutations. Fifteen novel variants that have not been previously reported were found. Moreover, p.L997F was identified as the most frequent pathogenic mutation that might affect the IRT measurements used for the NBS. The distribution of mutation frequencies in our study showed a difference from those previously reported; for example, the well-known p.F508del was the third most common (n = 42 alleles), rather than the first. The most striking finding is that 313 cases had a pathogenic variant together with the V470M variant, which might have a cumulative effect on CF perpetuation. Conclusion: This study is the first to determine the mutational spectrum of CFTR in correlation with the NBS program in the Turkish population. NBS for CF raises issues regarding screening in diverse populations, both medical and non-medical benefits, and carrier identification. Through the lens of NBS, we focused on the integrated diagnostic algorithms and their effect on the results of genetic testing.

A Peptide-Nucleic Acid Targeting miR-335-5p Enhances Expression of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Gene with the Possible Involvement of the CFTR Scaffolding Protein NHERF1.

(1) Background: Up-regulation of the Cystic Fibrosis Transmembrane Conductance Regulator gene (CFTR) might be of great relevance for the development of therapeutic protocols for cystic fibrosis (CF). MicroRNAs are deeply involved in the regulation of CFTR and scaffolding proteins (such as NHERF1, NHERF2 and Ezrin). (2) Methods: Content of miRNAs and mRNAs was analyzed by RT-qPCR, while the CFTR and NHERF1 production was analyzed by Western blotting. (3) Results: The results here described show that the CFTR scaffolding protein NHERF1 can be up-regulated in bronchial epithelial Calu-3 cells by a peptide-nucleic acid (PNA) targeting miR-335-5p, predicted to bind to the 3′-UTR sequence of the NHERF1 mRNA. Treatment of Calu-3 cells with this PNA (R8-PNA-a335) causes also up-regulation of CFTR. (4) Conclusions: We propose miR-335-5p targeting as a strategy to increase CFTR. While the efficiency of PNA-based targeting of miR-335-5p should be verified as a therapeutic strategy in CF caused by stop-codon mutation of the CFTR gene, this approach might give appreciable results in CF cells carrying other mutations impairing the processing or stability of CFTR protein, supporting its application in personalized therapy for precision medicine.

OTX2 regulates CFTR expression during endoderm differentiation and occupies 3' cis-regulatory elements.

Cell-specific and developmental mechanisms contribute to expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene; however, its developmental regulation is poorly understood. Here we use human induced pluripotent stem cells differentiated into pseudostratified airway epithelial cells to study these mechanisms. Changes in gene expression and open chromatin profiles were investigated by RNA-seq and ATAC-seq, and revealed that alterations in CFTR expression are associated with differences in stage-specific open chromatin. Additionally, two novel open chromatin regions, at +19.6 kb and +22.6 kb 3' to the CFTR translational stop signal, were observed in definitive endoderm (DE) cells, prior to an increase in CFTR expression in anterior foregut endoderm (AFE) cells. Chromatin studies in DE and AFE cells revealed enrichment of active enhancer marks and occupancy of OTX2 at these sites in DE cells. Loss of OTX2 in DE cells alters histone modifications across the CFTR locus and results in a 2.5-fold to 5-fold increase in CFTR expression. However, deletion of the +22.6 kb site alone does not affect CFTR expression in DE or AFE cells. These results suggest that a network of interacting cis-regulatory elements recruit OTX2 to the locus to impact CFTR expression during early endoderm differentiation.

Quantitative Evaluation of CFTR Pre-mRNA Splicing Dependent on the (TG)mTn Poly-Variant Tract.

Genetic analysis in cystic fibrosis (CF) is a difficult task. Within the many causes of variability and uncertainty, a major determinant is poor knowledge of the functional effect of most DNA variants of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. In turn, knowledge of the effect of a CFTR variant has dramatic diagnostic, prognostic and, in the era of CF precision medicine, also therapeutic consequences. One of the most challenging CFTR variants is the (TG)mTn haplotype, which has variable functional effect and controversial clinical consequences. The exact quantification of the anomalous splicing of CFTR exon 10 (in the HGVS name; exon 9 in the legacy name) and, consequently, of the residual wild-type functional CFTR mRNA, should be mandatory in clinical assessment of patients with potentially pathological haplotype of this tract. Here, we present a real time-based assay for the quantification of the proportion of exon 10+/exon 10− CFTR mRNA, starting from nasal brushing. Our assay proved rapid, economic and easy to perform. Specific primers used for this assay are either disclosed or commercially available, allowing any laboratory to easily perform it. A simplified analysis of the data is provided, facilitating the interpretation of the results. This method helps to enhance the comprehension of the genotype–phenotype relationship in CF and CFTR-related disorders (CFTR-RD), crucial for the diagnosis, prognosis and personalized therapy of CF.

Epidermal growth factor receptor activity upregulates lactate dehydrogenase A expression, lactate dehydrogenase activity, and lactate secretion in cultured IB3-1 cystic fibrosis lung epithelial cells.

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. It has been postulated that reduced HCO3- transport through CFTR may lead to a decreased airway surface liquid pH. In contrast, others have reported no changes in the extracellular pH (pHe). We have recently reported that in carcinoma Caco-2/pRS26 cells (transfected with short hairpin RNA for CFTR) or CF lung epithelial IB3-1 cells, the mutation in CFTR decreased mitochondrial complex I activity and increased lactic acid production, owing to an autocrine IL-1β loop. The secreted lactate accounted for the reduced pHe, because oxamate fully restored the pHe. These effects were attributed to the IL-1β autocrine loop and the downstream signaling kinases c-Src and JNK. Here we show that the pHe of IB3-1 cells can be restored to normal values (∼7.4) by incubation with the epidermal growth factor receptor (EGFR, HER1, ErbB1) inhibitors AG1478 and PD168393. PD168393 fully restored the pHe values of IB3-1 cells, suggesting that the reduced pHe is mainly due to increased EGFR activity and lactate. Also, in IB3-1 cells, lactate dehydrogenase A mRNA, protein expression, and activity are downregulated when EGFR is inhibited. Thus, a constitutive EGFR activation seems to be responsible for the reduced pHe in IB3-1 cells.