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Cystic Fibrosis (CF) is a genetic disease caused by mutations in CFTR gene expressing the anion selective channel CFTR located at the plasma membrane of different epithelial cells. The most commonly investigated variant causing CF is F508del. This mutation leads to structural defects in the CFTR protein, which are recognized by the endoplasmic reticulum (ER) quality control system. As a result, the protein is retained in the ER and degraded via the ubiquitin–proteasome pathway. Although blocking ubiquitination to stabilize the CFTR protein has long been considered a potential pharmacological approach in CF, progress in this area has been relatively slow. Currently, no compounds targeting this pathway have entered clinical trials for CF. On the other hand, the emergence of Orkambi initially, and notably the subsequent introduction of Trikafta/Kaftrio, have demonstrated the effectiveness of molecular chaperone-based therapies for patients carrying the F508del variant and even showed efficacy against other variants. These treatments directly target the CFTR variant protein without interfering with cell signaling pathways. This review discusses the limits and potential future of targeting protein ubiquitination in CF. [ABSTRACT FROM AUTHOR]

In vivo genome correction holds promise for generating durable disease cures; yet, effective stem cell editing remains challenging. In this work, we demonstrate that optimized lung-targeting lipid nanoparticles (LNPs) enable high levels of genome editing in stem cells, yielding durable responses. Intravenously administered gene-editing LNPs in activatable tdTomato mice achieved ’70% lung stem cell editing, sustaining tdTomato expression in ’80% of lung epithelial cells for 660 days. Addressing cystic fibrosis (CF), NG-ABE8e messenger RNA (mRNA)-sgR553X LNPs mediated ’95% cystic fibrosis transmembrane conductance regulator (CFTR) DNA correction, restored CFTR function in primary patient-derived bronchial epithelial cells equivalent to Trikafta for F508del, corrected intestinal organoids and corrected R553X nonsense mutations in 50% of lung stem cells in CF mice. These findings introduce LNP-enabled tissue stem cell editing for disease-modifying genome correction. [ABSTRACT FROM AUTHOR]

This article, titled "Poster abstracts," discusses the risk of psoriasis related to the use of angiotensin-converting enzyme inhibitors (ACEIs). The authors conducted a study using the WHO pharmacovigilance database VigiBase® to verify the presence of a safety signal. They identified 467 reports of psoriasis after ACEI exposure, with plaque psoriasis being the most prevalent form. The study found a safety signal with a reporting odds ratio (ROR) of 2.96, and the strongest signals were observed for erythrodermic psoriasis and pustular psoriasis. The authors recommend that prescribers be vigilant for the onset of psoriasis-like skin lesions during the first year of ACEI exposure and consider a switch if necessary. [Extracted from the article]

SARS-CoV-2 infection has been recently shown to induce cellular senescence in vivo. A senescence-like phenotype has been reported in cystic fibrosis (CF) cellular models. Since the previously published data highlighted a low impact of SARS-CoV-2 on CFTR-defective cells, here we aimed to investigate the senescence hallmarks in SARS-CoV-2 infection in the context of a loss of CFTR expression/function. We infected WT and CFTR KO 16HBE14o-cells with SARS-CoV-2 and analyzed both the p21 and Ki67 expression using immunohistochemistry and viral and p21 gene expression using real-time PCR. Prior to SARS-CoV-2 infection, CFTR KO cells displayed a higher p21 and lower Ki67 expression than WT cells. We detected lipid accumulation in CFTR KO cells, identified as lipolysosomes and residual bodies at the subcellular/ultrastructure level. After SARS-CoV-2 infection, the situation reversed, with low p21 and high Ki67 expression, as well as reduced viral gene expression in CFTR KO cells. Thus, the activation of cellular senescence pathways in CFTR-defective cells was reversed by SARS-CoV-2 infection while they were activated in CFTR WT cells. These data uncover a different response of CF and non-CF bronchial epithelial cell models to SARS-CoV-2 infection and contribute to uncovering the molecular mechanisms behind the reduced clinical impact of COVID-19 in CF patients. [ABSTRACT FROM AUTHOR]

Anoctamin1 (ANO1), a calcium-activated chloride channel, is overexpressed in a variety of cancer cells, including prostate cancer, and is involved in cancer cell proliferation, migration, and invasion. Inhibition of ANO1 in these cancer cells exhibits anticancer effects. In this study, we conducted a screening to identify novel ANO1 inhibitors with anticancer effects using PC-3 human prostate carcinoma cells. Screening of 2978 approved and investigational drugs revealed that hemin is a novel ANO1 inhibitor with an IC50 value of 0.45 μM. Notably, hemin had no significant effect on intracellular calcium signaling and cystic fibrosis transmembrane conductance regulator (CFTR), a cyclic AMP (cAMP)-regulated chloride channel, and it showed a weak inhibitory effect on ANO2 at 3 μM, a concentration that completely inhibits ANO1. Interestingly, hemin also significantly decreased ANO1 protein levels and strongly inhibited the cell proliferation and migration of PC-3 cells in an ANO1-dependent manner. Furthermore, it strongly induced caspase-3 activation, PARP degradation, and apoptosis in PC-3 cells. These findings suggest that hemin possesses anticancer properties via ANO1 inhibition and could be considered for development as a novel treatment for prostate cancer. [ABSTRACT FROM AUTHOR]

Objectives Despite the introduction of cystic fibrosis transmembrane conductance regulator (CFTR) modulators, Pseudomonas aeruginosa is still a major pathogen in people with cystic fibrosis (pwCF). We determine the activity of cefiderocol and comparators in a collection of 154 P. aeruginosa isolates recovered from pwCF during three multicentre studies performed in 17 Spanish hospitals in 2013, 2017 and 2021. Methods ISO broth microdilution was performed and MICs were interpreted with CLSI and EUCAST criteria. Mutation frequency and WGS were also performed. Results Overall, 21.4% were MDR, 20.8% XDR and 1.3% pandrug-resistant (PDR). Up to 17% of the isolates showed a hypermutator phenotype. Cefiderocol demonstrated excellent activity; only 13 isolates (8.4%) were cefiderocol resistant by EUCAST (none using CLSI). A high proportion of the isolates resistant to ceftolozane/tazobactam (71.4%), meropenem/vaborbactam (70.0%), imipenem/relebactam (68.0%) and ceftazidime/avibactam (55.6%) were susceptible to cefiderocol. Nine out of 13 cefiderocol-resistant isolates were hypermutators (P  < 0.001). Eighty-three STs were detected, with ST98 being the most frequent. Only one isolate belonging to the ST175 high-risk clone carried bla VIM-2. Exclusive mutations affecting genes involved in membrane permeability, AmpC overexpression (L320P-AmpC) and efflux pump up-regulation were found in cefiderocol-resistant isolates (MIC = 4–8 mg/L). Cefiderocol resistance could also be associated with mutations in genes related to iron uptake (tonB -dependent receptors and pyochelin/pyoverdine biosynthesis). Conclusions Our results position cefiderocol as a therapeutic option in pwCF infected with P. aeruginosa resistant to most recent β-lactam/β-lactamase inhibitor combinations. [ABSTRACT FROM AUTHOR]

Introduction: Hypoxia due to sinus obstruction is a major pathogenic mechanism leading to sinusitis. The objective of the current study is to define the electrophysiologic characteristics of hypoxia in vitro and in vivo. Methods: Cystic fibrosis bronchoepithelial cells expressing wild‐type cystic fibrosis transmembrane conductance regulator (CFTR) and human sinonasal epithelial cells were exposed to 1% or atmospheric O2 for 24 h. Time‐dependent production of cytoplasmic free radicals was measured. Cells were subjected to Ussing chamber and patch clamp technique where CFTR currents were recorded in whole‐cell and cell‐attached mode for single channel studies. Indices of mucociliary transport (MCT) were measured using micro‐optical coherence tomography. In a rabbit hypoxic maxillary sinus model, tissue oxygenation, relative mRNA expression of HIF‐1α, pH, sinus potential difference (SPD), and MCT were determined. Results: Ussing chamber (p < 0.05), whole‐cell (p < 0.001), and single channel patch‐clamp (p < 0.0001) showed significant inhibition of Cl− currents in hypoxic cells. Cytoplasmic free radicals showed time‐dependent elevation peaking at 4 h (p < 0.0001). Airway surface liquid (p < 0.0001), periciliary liquid (p < 0.001), and MCT (p < 0.01) were diminished. Co‐incubation with the free radical scavenger glutathione negated the impact of hypoxia on single channel currents and MCT markers. In sinusitis rabbits, mucosa exhibited low tissue oxygenation (p < 0.0001), increased HIF1α mRNA (p < 0.05), reduced pH (p < 0.01), and decreased MCT (p < 0.001). SPD measurements demonstrated markedly diminished transepithelial Cl− transport (p < 0.0001). Conclusion: Hypoxia induces severe CFTR dysfunction via free radical production causing reduced MCT in vitro and in vivo. Improved oxygenation is critical to reducing the impact of persistent mucociliary dysfunction. [ABSTRACT FROM AUTHOR]

Cystic fibrosis (CF) is an autosomal recessive disorder caused by mutations in the CFTR gene. This study aimed to identify the spectrum of CFTR variants reported in individuals with CF from South Asia (ISA). We conducted a PubMed search for CFTR variants reported in ISA. Full text of original articles and case reports was read to compile data on reported variants. To gather additional data, we independently cross-referenced each variant with the CFTR Mutation Database and ClinVar. Our investigation identified a total of 92 CFTR variants reported across 30 articles. The most frequently tested, and reported variant was ΔF508 with a global frequency of 69.74%. Notably, we found 14 pathogenic CFTR mutations shared among ISA, originating from more than one South Asian country: ΔF508, 1525-1 G > A, G542X, S549N, R117H, S549R, R709X, V456A, Y569D, L1077P, 1161delC, 1898 + 1 G > T, G551D, and 2184insA. In summary, the higher prevalence of consanguinity and the limited availability of CF diagnostic resources in South Asia considerably contribute to the prevalence of genetic disorders like CF. The spectrum of CFTR mutations exhibits noticeable variations within South Asian and other populations. The inclusion of current study-enlisted CFTR gene variants is highly recommended for CF disease genetic testing in South Asia which may aid in achieving a precise diagnosis, enhancing disease management, and discovering drugs for currently untreatable genetic variants. It is also imperative to conduct a comprehensive study in this region, especially in previously unexplored countries such as Nepal, Bhutan, Maldives, and Bangladesh. [ABSTRACT FROM AUTHOR]

Background: Cystic fibrosis (CF) is a rare multi-systemic recessive disorder. The spectrum and the frequencies of CFTR mutations causing CF vary amongst different populations in Europe and the Middle East. In this study, we characterised the distribution of CF-causing mutations (i.e. pathogenic variants in the CFTR gene) in a representative CF cohort from the Kingdom of Bahrain based on a three-decade-long analysis at a single tertiary centre. We aim to improve CF genetic diagnostics, introduce of CF neonatal screening and provide CFTR modulator therapy (CFTRm). Methods: CFTR genotyping and associated clinical information were drawn from a longitudinal cohort. We sequenced 56 people with CF (pwCF) that had one or both CFTR mutations unidentified and carried out comprehensive bioinformatic- and family-based segregation analyses of detected variants, including genotype–phenotype correlations and disease incidence estimates. The study methodology could serve as a basis for other non-European CF populations with a high degree of consanguinity. Results: Altogether 18 CF-causing mutations were identified, 15 of which were not previously detected in Bahrain, accounting for close to 100% of all population-specific alleles. The most common alleles comprise c.1911delG [2043delG; 22.8%], c.2988+1G > A [3120+1G>A; 16.3%], c.2989-1G>A [3121-1G>A; 14.1%], c.3909C>G [N1303K; 13.0%], and c.1521_1523delCTT [p.PheF508del; 7.6%]. Although the proportion of 1st cousin marriages has decreased to 50%, the frequency of homozygosity in our pwCF is 67.4%, thereby indicating that CF still occurs in large, often related, families. pwCF in Bahrain present with faltering growth, pancreatic insufficiency and classical sino-pulmonary manifestations. Interestingly, two pwCF also suffer from sickle cell disease. The estimated incidence of CF in Bahrain based on data from the last three decades is 1 in 9,880 live births. Conclusion: The most commonCF-causing mutations in Bahraini pwCF were identified, enabling more precise diagnosis, introduction of two-tier neonatal screening and fostering administration of CFTRm. [ABSTRACT FROM AUTHOR]

• In this cohort of infants, ivacaftor treatment: • Achieved exposures in range of clinical studies in other age groups. • Was generally safe and well-tolerated. • Led to improvements in CFTR function and growth parameters. • Resulted in improvements in pancreatic function and intestinal inflammation markers. Ivacaftor (IVA) has been shown to be safe and efficacious in children aged ≥4 months with cystic fibrosis (CF) and CFTR gating variants. We evaluated safety, pharmacokinetics (PK), and efficacy of IVA in a small cohort of infants aged 1 to <4 months with CF. In this phase 3, open-label study, infants 1 to <4 months with CF and an IVA-responsive CFTR variant received an initial low dose of IVA based on age and weight. Because IVA is a sensitive CYP3A substrate and CYP3A maturation is uncertain in infants, doses were adjusted at day 15 to better match median adult exposures based on individual PK measurements taken on day 4. Primary endpoints were safety and PK measurements. Seven infants (residual function CFTR variants [ n= 5]; minimal function CFTR variants [ n= 2]) received ≥1 dose of IVA. Six infants had doses adjusted at day 15 and one infant did not require dose adjustment; subsequent PK analyses showed mean trough concentrations for IVA and metabolites were within range of prior clinical experience. Four infants (57.1%) had adverse events (AEs); no serious AEs were noted. One infant discontinued study drug due to a non-serious AE of elevated alanine aminotransferase >8x the upper limit of normal. Mean sweat chloride concentration decreased (−40.3 mmol/L [SD: 29.2]) through week 24. Improvements in biomarkers of pancreatic function and intestinal inflammation, as well as growth parameters, were observed. In this small, open-label study, IVA dosing in infants achieved exposures previously shown to be safe and efficacious. Because PK was predictable, a dosing regimen based on age and weight is proposed. IVA was generally safe and well tolerated, and led to improvements in CFTR function, markers of pancreatic function and intestinal inflammation, and growth parameters, supporting use in infants as young as 1 month of age. [ABSTRACT FROM AUTHOR]

• aCFLD had higher S. salivarius and V. parvula fecal abundances compared to CFnoLD. • Both species decreased after ETI in subjects with aCFLD and calprotectin decrease. • This supports the gut-liver axis linking dysbiosis, intestinal inflammation & aCFLD. Cystic fibrosis associated liver disease (CFLD) carries a significant disease burden with no effective preventive therapies. According to the gut-liver axis hypothesis for CFLD pathogenesis, dysbiosis and increased intestinal inflammation and permeability permit pathogenic bacterial translocation into the portal circulation, leading to hepatic inflammation and fibrosis. Evaluating the effect of CFTR (cystic fibrosis transmembrane conductance regulator) modulation with elexacaftor/tezacaftor/ivacaftor (ETI) may help determine the role of CFTR in CFLD and increase understanding of CFLD pathogenesis, which is critical for developing therapies. We aimed to characterize the fecal microbiota in participants with CF with and without advanced CFLD (aCFLD) before and after ETI. This is an ancillary analysis of stool samples from participants ages ≥12 y/o enrolled in PROMISE (NCT04038047). Included participants had aCFLD (cirrhosis with or without portal hypertension, or non-cirrhotic portal hypertension) or CF without liver disease (CFnoLD). Fecal microbiota were defined by shotgun metagenomic sequencing at baseline and 1 and 6 months post-ETI. We analyzed 93 samples from 34 participants (11 aCFLD and 23 CFnoLD). Compared to CFnoLD, aCFLD had significantly higher baseline relative abundances of potential pathogens Streptococcus salivarius and Veillonella parvula. Four of 11 aCFLD participants had an initially abnormal fecal calprotectin that normalized 6 months post-ETI, correlating with a significant decrease in S. salivarius and a trend towards decreasing V. parvula. These results support an association between dysbiosis and intestinal inflammation in CFLD with improvements in both post-ETI, lending further support to the gut-liver axis in aCFLD. [ABSTRACT FROM AUTHOR]

• Advantages and challenges of a dedicated patient registry for people with CFTR-RD. • The CFTR-RD risk for infants with a CRMS/CFSPID designation. • Peculiarities of genetic counseling in people and families with CFTR-RD. • Identification of barriers to disseminate, implement and monitor CFTR-RD management. • Feasibility of clinical trials in people with CFTR-RD. After three publications defining an updated guidance on the diagnostic criteria for people with cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (pwCFTR-RDs), establishing its relationship to CFTR-dysfunction and describing the individual disorders, this fourth and last paper in the series addresses some critical challenges facing health care providers and pwCFTR-RD. Topics included are: 1) benefits and obstacles to collect data from pwCFTR-RD are discussed, together with the opportunity to integrate them into established CF-registries; 2) the potential of infants designated CRMS/CFSPID to develop a CFTR-RD and how to communicate this information; 3) a description of the challenges in genetic counseling, with particular regard to phenotypic variability, unknown long-term evolution, CFTR testing and pregnancy termination 4) a proposal for the assessment of potential barriers to the implementation and dissemination of the produced documents to health care professionals involved in the care of pwCFTR-RD and a process to monitor the implementation of the CFTR-RD recommendations; 5) clinical trials investigating the efficacy of CFTR modulators in CFTR-RD and how endpoints and outcomes might be adapted to the heterogeneity of these disorders. [ABSTRACT FROM AUTHOR]

• Three patient cases suggest addition of rifabutin does not compromise ETI efficacy. • PBPK simulated ETI lung concentrations with concomitant rifabutin remain therapeutic. • The study supports the use of rifabutin for the treatment of NTM in CF receiving ETI. The concomitant use of elexacaftor/tezacaftor/ivacaftor (ETI) and strong CYP3A inducers including rifampin and rifabutin is not recommended due to the risk of drug-drug interactions (DDI). This presents a significant challenge to the treatment of non-tuberculous mycobacteria precluding the first line treatment. While rifabutin induces CYP3A activity, its effect appears to be moderate compared to rifampin. In this study, we investigated three cases in which concomitant use of rifabutin and CFTR modulators (ETI or ivacaftor monotherapy) was used, and these cases suggest that addition of rifabutin did not compromise the efficacy of ETI or ivacaftor as evidenced by pulmonary function and sweat chloride testing. A full physiologically based pharmacokinetic model predicted lung concentrations of ETI upon rifabutin coadministration to exceed the half-maximal effective concentrations (EC 50) determined from chloride transport in phe508del human bronchial epithelial cells. This study provides preliminary evidence in support of the use of rifabutin in patients receiving ETI. [ABSTRACT FROM AUTHOR]

• Inhaled antimicrobial prescribing process is multifactorial. • Nebulised tobramycin or colistin are commonly used first-line therapies. • CFTR modulator use may not affect how some physicians prescribe inhaled antibiotics. Prescribers have an increasing range of inhaled antimicrobial formulations to choose from when prescribing both eradication and chronic suppression regimens in cystic fibrosis (CF). This study aimed to investigate the decision-making process behind prescribing of inhaled antimicrobials for Pseudomonas aeruginosa infections. A questionnaire was developed using Microsoft Forms and then forwarded to 57 Principal Investigators (PIs), at each of the CF centres within the European Cystic Fibrosis Society-Clinical Trials Network (ECFS-CTN). Data collection occurred between November 2021 and February 2022. The response rate was 90 % (n = 51/57 PIs), with at least 50 % of CF centers in each of the 17 countries represented in the ECFS-CTN. Physicians used a median of eight factors in their decision-making process with delivery formulations (92.2 %), adherence history (84.3 %), and antibiotic side-effect profile (76.5 %) often selected. Nebulised tobramycin or colistin were frequently selected as the inhaled antimicrobial in first-line eradication (n = 45, 88.2 %) and chronic suppression regimens (n = 42, 82.4 %). Combination regimens were more often chosen in eradication (first-line: n = 35, 68.6 %, second-line: n = 34, 66.7 %) and later chronic suppression regimens (third-line: n = 27, 52.9 %) than monotherapy. For pwCF also prescribed CFTR modulator therapies, most PIs did not alter inhaled antimicrobial regimens (n = 40, 78.4 %), with few pwCF (n = 18, 35.3 %) or PIs (n = 10, 19.6 %) deciding to stop inhaled antimicrobials. The inhaled antimicrobial prescribing decision-making process is multifactorial. Nebulised tobramycin or colistin are often used in initial eradication and chronic suppression regimens. To date, CFTR modulator therapy has had a limited impact on the prescribing of inhaled antimicrobial regimens. [ABSTRACT FROM AUTHOR]

• The number of males with CF (mwCF) who are becoming fathers is increasing. • Safety of modulator use by mwCF during conception and partner pregnancy is unknown. • For exposed fetuses, miscarriage rates were consistent with US population rates. • No congenital anomalies were reported for exposed infants. • A prospective study is needed to study modulator use by mwCF during reproduction. Most males with cystic fibrosis (mwCF) are infertile but with CF transmembrane conductance regulator (CFTR) modulator-conferred benefits, more are utilizing assisted reproductive technologies (ART). Administration of normal human doses of modulators in animal reproductive models caused no genotoxicity; no human data exists. Potential health decline following modulator discontinuation makes the decision to withhold therapy during reproduction challenging. From August-October 2021, international CF clinicians completed an anonymous questionnaire regarding mwCF who used modulators during reproduction. We received 42 surveys for mwCF with partner pregnancies. Forty of 42 mwCF utilized ART; 35 continued modulators during sperm retrieval and 40/42 during partner pregnancy. One of four males who discontinued modulators experienced clinical deterioration. First trimester miscarriages occurred in 11.9 % of partner pregnancies. No congenital anomalies were reported. Use of CFTR modulators during reproduction and partner pregnancy in mwCF did not result in a higher-than-expected miscarriage rate nor congenital anomalies. [ABSTRACT FROM AUTHOR]

• Early weight-for-length (WFL)/body mass index (BMI) growth trajectories are not associated with pubertal outcomes in people with cystic fibrosis (CF), but height at age 2 years is. • Initiating CFTR modulator therapy in childhood is associated with taller adult height even after adjusting for early growth. • Future research should explore the evolving impact of highly effective modulator therapy (HEMT) use in early childhood on pubertal growth outcomes in CF. Pubertal delays in children with cystic fibrosis (CF) have historically been common. It is unclear to what degree puberty is affected in the new era of CF care or the role of early nutritional status. We hypothesized that more favorable early growth trajectories are associated with improved pubertal growth outcomes. We used data from the United States CF Foundation Patient Registry to analyze associations between early weight-for-length/body mass index (WFL-BMI) growth trajectories and pubertal outcomes, using peak height velocity (PHV) and age at PHV (APHV) as proxy measures for puberty in addition to adult height (defined as height at age 18 years). Our analysis consisted of shape invariant mixed modeling and multivariable linear regression. Our sample consisted of 9,186 people with CF aged 18 to 21 years between 2010-2019. APHV was earliest and PHV/adult height were highest in those with WFL-BMI always >50th percentile from 0-6 years. However, there was no difference after adjusting for key covariates. Receiving CF transmembrane conductance regulator (CFTR) modulator therapy in childhood was associated with being taller at 18 years, by 0.92 cm in males (p=0.048) and 1.02 cm in females (p=0.010) in adjusted models. Higher height z-score at 2 years was associated with improved APHV and PHV for males and improved adult height for both males and females (p<0.001) in adjusted models. Early height, but not early WFL-BMI trajectories, may be associated with pubertal growth outcomes. CFTR modulator therapy shows the potential to improve pubertal growth outcomes, but further research is necessary. [ABSTRACT FROM AUTHOR]

• We surveyed lung transplant recipients' perspectives on ETI use after transplant. • Over 80 % of respondents said treating non-pulmonary CF symptoms is very important. • Two-thirds felt comfortable with taking ETI based on their current knowledge. • Concerns included potential drug interactions, side effects, and cost of ETI. Cystic fibrosis transmembrane conductance regulator (CFTR) modulators, including elexacaftor/tezacaftor/ivacaftor (ETI), significantly improve outcomes and quality of life for people with cystic fibrosis (CF). However, little is known about how lung transplant recipients (LTRs) perceive the use of ETI. We conducted a survey to assess perspectives on ETI among LTRs with CF at our lung transplant program. Of 81 CF LTRs, 46 participants (58 %) responded. The majority of respondents (88 %) were aware of ETI. Over 80 % considered treating non-lung symptoms of CF to be very important. Concerns regarding ETI included potential drug interactions with transplant medications (77 %), side effects (53 %), cost of medication (49 %), and lack of clinical trial data for LTRs (43 %). Half reported they would only consider taking ETI if their CF or transplant doctor recommended it. The findings suggest that CF LTRs seek informational support and shared decision-making about ETI from their clinicians. [ABSTRACT FROM AUTHOR]

This research note discusses the role of individual sinus inflammation in chronic rhinosinusitis (CRS) and olfaction after highly effective modulator therapy. The study found that individual sinus opacification (ISO) can be measured using a convolutional neural network approach. ISO decreased over a two-year period after initiating modulator therapy. However, ISO did not correlate with quality of life or olfaction in adults with cystic fibrosis. The study highlights the importance of understanding disease in specific sinuses for targeted treatments. Another article discusses the relationship between sinus opacification (SO) and patient outcomes in individuals with cystic fibrosis (CF) who have undergone highly effective modulator therapy. The study found that greater sphenoid SO was correlated with worse rhinologic and extranasal rhinologic scores after 24 months of therapy. However, the clinical significance of this correlation is unknown. The study also found that there was no consistent correlation between SO and other outcome measures such as health utility value and smell identification test scores. The findings suggest that further research is needed to understand the impact of individual sinus inflammation on chronic rhinosinusitis and olfaction in individuals with CF. [Extracted from the article]

Cystic fibrosis (CF) is a genetic disease caused by the mutations of cystic fibrosis transmembrane conductance regulator (CFTR), the cystic fibrosis transmembrane conductance regulator gene. Cftr is a critical ion channel expressed in the apical membrane of mouse salivary gland striated duct cells. Although Cftr is primarily a Cl− channel, its knockout leads to higher salivary Cl− and Na+ concentrations and lower pH. Mouse experiments show that the activation of Cftr upregulates epithelial Na+ channel (ENaC) protein expression level and Slc26a6 (a 1Cl−:2 HCO 3 − exchanger of the solute carrier family) activity. Experimentally, it is difficult to predict how much the coregulation effects of CFTR contribute to the abnormal Na+, Cl−, and HCO 3 − concentrations and pH in CF saliva. To address this question, we construct a wild-type mouse salivary gland model and simulate CFTR knockout by altering the expression levels of CFTR, ENaC, and Slc26a6. By reproducing the in vivo and ex vivo final saliva measurements from wild-type and CFTR knockout animals, we obtain computational evidence that ENaC and Slc26a6 activities are downregulated in CFTR knockout in salivary glands. NEW & NOTEWORTHY: This paper describes a salivary gland mathematical model simulating the ion exchange between saliva and the salivary gland duct epithelium. The novelty lies in the implementation of CFTR regulating ENaC and Slc26a6 in a CFTR knockout gland. By reproducing the experimental saliva measurements in wild-type and CFTR knockout glands, the model shows that CFTR regulates ENaC and Slc26a6 anion exchanger in salivary glands. The method could be used to understand the various cystic fibrosis phenotypes. [ABSTRACT FROM AUTHOR]

Calcitonin gene-related peptide (CGRP) has long been implicated in both the physiology and pathophysiology of the respiratory tract. The objective of our study was to determine the serum concentration of alpha CGRP (αCGRP) in cystic fibrosis (CF) that arises from mutations in the gene responsible for encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Currently, there are not many data in the literature about the role of CGRP in CF. The serum level of αCGRP was estimated using the enzyme-linked immunosorbent assay among 64 patients with CF and 31 healthy controls. The αCGRP concentration in the CF group was 62.51 ± 15.45 pg/mL, while in the control group it was 47.43 ± 8.06 pg/mL (p < 0.001). We also compared the level of αCGRP in CF patients according to the type of CFTR mutation. Homozygotes for ΔF508 had higher αCGRP levels than heterozygotes (67.9 ± 10.2 vs. 54.5 ± 18.3 pg/mL, p < 0.01). The level of this neuropeptide was statistically higher in patients with severe disease than in those with mild CF (p = 0.003) when patients were divided into three groups by spirometry results. αCGRP concentration was not correlated with age, sex, clinical parameters, and pulmonary function test results in the study participants. The results of our study suggest a significant increase in the concentration of αCGRP in the serum of patients with CF compared to the control group. This observation opens interesting possibilities for understanding the role of αCGRP in the context of CF pathophysiology. [ABSTRACT FROM AUTHOR]

Background: Pulmonary ionocytes have been identified in the airway epithelium as a small population of ion transporting cells expressing high levels of CFTR (cystic fibrosis transmembrane conductance regulator), the gene mutated in cystic fibrosis. By providing an infinite source of airway epithelial cells (AECs), the use of human induced pluripotent stem cells (hiPSCs) could overcome some challenges of studying ionocytes. However, the production of AEC epithelia containing ionocytes from hiPSCs has proven difficult. Here, we present a platform to produce hiPSC-derived AECs (hiPSC-AECs) including ionocytes and investigate their role in the airway epithelium. Methods: hiPSCs were differentiated into lung progenitors, which were expanded as 3D organoids and matured by air-liquid interface culture as polarised hiPSC-AEC epithelia. Using CRISPR/Cas9 technology, we generated a hiPSCs knockout (KO) for FOXI1, a transcription factor that is essential for ionocyte specification. Differences between FOXI1 KO hiPSC-AECs and their wild-type (WT) isogenic controls were investigated by assessing gene and protein expression, epithelial composition, cilia coverage and motility, pH and transepithelial barrier properties. Results: Mature hiPSC-AEC epithelia contained basal cells, secretory cells, ciliated cells with motile cilia, pulmonary neuroendocrine cells (PNECs) and ionocytes. There was no difference between FOXI1 WT and KO hiPSCs in terms of their capacity to differentiate into airway progenitors. However, FOXI1 KO led to mature hiPSC-AEC epithelia without ionocytes with reduced capacity to produce ciliated cells. Conclusion: Our results suggest that ionocytes could have role beyond transepithelial ion transport by regulating epithelial properties and homeostasis in the airway epithelium. [ABSTRACT FROM AUTHOR]

Solute carrier family 26 member 4 (SLC26A4) is a member of the SLC26A transporter family and is expressed in various tissues, including the airway epithelium, kidney, thyroid, and tumors. It transports various ions, including bicarbonate, chloride, iodine, and oxalate. As a multiple-ion transporter, SLC26A4 is involved in the maintenance of hearing function, renal function, blood pressure, and hormone and pH regulation. In this review, we have summarized the various functions of SLC26A4 in multiple tissues and organs. Moreover, the relationships between SLC26A4 and other channels, such as cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, and sodium chloride cotransporter, are highlighted. Although the modulation of SLC26A4 is critical for recovery from malfunctions of various organs, development of specific inducers or agonists of SLC26A4 remains challenging. This review contributes to providing a better understanding of the role of SLC26A4 and development of therapeutic approaches for the SLC26A4-associated hearing loss and SLC26A4-related dysfunction of various organs. [ABSTRACT FROM AUTHOR]

Inflammation-associated fibroblasts (IAFs) are associated with progression and drug resistance of chronic inflammatory diseases such as inflammatory bowel disease (IBD), but their direct impact on epithelial cells is unknown. Here, we developed an in vitro model whereby human colon fibroblasts are induced by specific cytokines and recapitulate key features of IAFs in vivo. When cocultured with patient-derived colon organoids (colonoids), IAFs induced rapid colonoid expansion and barrier disruption due to swelling and rupture of individual epithelial cells. Colonoids cocultured with IAFs also show increased DNA damage, mitotic errors, and proliferation arrest. These IAF-induced epithelial defects are mediated by a paracrine pathway involving prostaglandin E2 and its receptor EP4, leading to protein kinase A -dependent activation of the cystic fibrosis transmembrane conductance regulator. EP4-specific chemical inhibitors effectively prevented IAF-induced colonoid swelling and restored normal proliferation and genome stability. These findings reveal a mechanism by which IAFs could promote and perpetuate IBD and suggest a therapeutic avenue to mitigate inflammation-associated epithelial injury. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Role of Hydrophobic Amino-Acid Side-Chains in the Narrow Selectivity Filter of the CFTR Chloride Channel Pore in Conductance and Selectivity" published in the Journal of Membrane Biology. The original article contained errors in the figure captions, and this correction provides the correct captions for Figures 1 to 8. The figures present information on the structure of the CFTR pore region, single channel conductance of channel mutants, thiocyanate permeability of channel mutants, properties of lysine-substituted channel mutants, and single channel conductance of R334-mutant channels. The original article has been corrected. [Extracted from the article]

The transcription factor farnesoid X receptor (FXR) regulates energy metabolism. Specifically, FXR functions to regulate cystic fibrosis transmembrane conductance regulator (CFTR)-mediated Cl– secretion in intestinal epithelial cells. Therefore, this study aimed to investigate the role of FXR in CFTR-mediated Cl– secretion in renal tubular cells and to further elucidate its effects on renal cyst formation and growth. CFTR-mediated Cl– transport was evaluated via short-circuit current (ISC) measurements in Madin–Darby canine kidney (MDCK) cell monolayers and primary rat inner medullary collecting duct cells. The role of FXR in renal cyst formation and growth was determined by the MDCK cell-derived cyst model. Incubation with synthesized (GW4064) and endogenous (CDCA) FXR ligands reduced CFTR-mediated Cl– secretion in a concentration- and time-dependent manner. The inhibitory effect of FXR ligands was not due to the result of reduced cell viability and was attenuated by cotreatment with an FXR antagonist. FXR activation significantly decreased CFTR protein but not its mRNA. In addition, FXR activation inhibited CFTR-mediated Cl– secretion in primary renal collecting duct cells. FXR activation decreased ouabain-sensitive ISC without altering Na+-K+-ATPase mRNA and protein levels. Furthermore, FXR activation significantly reduced the number of cysts and renal cyst expansion. These inhibitory effects were correlated with a decrease in the expression of protein synthesis regulators mammalian target of rapamycin/S6 kinase. This study shows that FXR activation inhibits Cl– secretion in renal cells via inhibition of CFTR expression and retards renal cyst formation and growth. The discoveries point to a physiological role of FXR in the regulation of CFTR and a potential therapeutic application in polycystic kidney disease treatment. NEW & NOTEWORTHY: The present study reveals that farnesoid X receptor (FXR) activation reduces microcyst formation and enlargement. This inhibitory effect of FXR activation is involved with decreased cell proliferation and cystic fibrosis transmembrane conductance regulator-mediated Cl– secretion in renal collecting duct cells. FXR might represent a novel target for the treatment of autosomal dominant polycystic kidney disease. [ABSTRACT FROM AUTHOR]

The formation of calcium oxalate (CaOx) crystals in the kidneys leads to renal epithelial damage and the progression of crystalline nephropathy. This study investigated the role of STIP1 homology and U-box protein 1 (STUB1), an E3 ubiquitin ligase, and cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel, in CaOx-related renal damage and autophagy regulation. HK-2 cells were treated with various doses of CaOx monohydrate (COM) to simulate kidney injury in vitro. Cell viability, reactive oxygen species (ROS) production, and apoptosis were assessed. The regulation of CFTR ubiquitination by STUB1 was confirmed by immunoprecipitation. An in vivo model was established by injecting mice with glyoxylate. COM treatment dose-dependently decreased cell viability, increased TNF-α and ROS production, and induced apoptotic cell death in HK-2 cells. COM-treated cells also showed decreased CFTR protein expression. CFTR overexpression improved cell viability and reduced ROS production in COM-stimulated HK-2 cells. Bioinformatics analysis predicted CFTR's ubiquitination binding site for STUB1. Further analysis confirmed the role of STUB1 as a ubiquitin ligase in CFTR degradation. Knockdown of STUB1 upregulated CFTR expression, while STUB1 overexpression had the opposite effect. Knockdown of CFTR reversed the impact of STUB1 deficiency on autophagy. The in vivo experiments showed that CFTR overexpression attenuated kidney tissue damage and CaOx deposition in mice. STUB1-mediated CFTR ubiquitination plays a crucial role in mitigating calcium oxalate-related renal damage by regulating autophagy. Targeting the STUB1/CFTR axis may hold therapeutic potential for treating kidney injury associated with calcium oxalate deposition. [ABSTRACT FROM AUTHOR]

Cystic fibrosis (CF) is a life-threatening monogenic disease affecting thousands of people worldwide. Cystic fibrosis transmembrane conductance regulator (CFTR) is an ion channel that facilitates transportation of water and salts across epithelial cell membranes through the conductance of Cl− and other anions. A dysfunctional CFTR due to abnormalities in the cftr gene causes CF, which is believed to be a rare disease in India mainly due to mis/underdiagnosis. Although numerous diagnostic methods and treatment options are available for CF globally, most of these are unaffordable for developing countries like India. Currently, CF symptoms are managed with mucolytics, antibiotics, anti-inflammatory drugs, and various CFTR modulators based on the type of defect. While a definitive cure for CF remains elusive, advancements in stem cell and gene therapies hold promise for permanent cure in the near future. In this review, we discuss the prevalence of CF cases in India, affordable diagnostic methods, and treatment options amenable for developing countries. We further emphasize the scope for the universal newborn screening programme. [ABSTRACT FROM AUTHOR]

Background: Limited understanding of the diversity of variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene across ancestries hampers efforts to advance molecular diagnosis of cystic fibrosis (CF). The consequences pose a risk of delayed diagnoses and subsequently worsened health outcomes for patients. Therefore, characterizing the spectrum of CFTR variants across ancestries is critical for revolutionizing molecular diagnoses of CF. Methods: We analyzed 454,727 UK Biobank (UKBB) whole-exome sequences to characterize the diversity of CFTR variants across ancestries. Using the PanUKBB classification, the participants were assigned into six major groups: African (AFR), American/American Admixed (AMR), Central South Asia (CSA), East Asian (EAS), European (EUR), and Middle East (MID). We segregated ancestry-specific CFTR variants, including those that are CF-causing or clinically relevant. The ages of certain CF-causing variants were determined and analyzed for selective pressure effects, and curated phenotype analysis was performed for participants with clinically relevant CFTR genotypes. Results: We detected over 4000 CFTR variants, including novel ancestry-specific variants, across six ancestries. Europeans had the most unique CFTR variants [n = 2212], while the American group had the least unique variants [n = 23]. F508del was the most prevalent CF-causing variant found in all ancestries, except in EAS, where V520F was the most prevalent. Common EAS variants such as 3600G > A, V456A, and V520, which appeared approximately 270, 215, and 338 generations ago, respectively, did not show evidence of selective pressure. Sixteen participants had two CF-causing variants, with two being diagnosed with CF. We found 154 participants harboring a CF-causing and varying clinical consequences (VCC) variant. Phenotype analysis performed for participants with multiple clinically relevant variants returned significant associations with CF and its pulmonary phenotypes [Bonferroni-adjusted p < 0.05]. Conclusions: We leveraged the UKBB database to comprehensively characterize the broad spectrum of CFTR variants across ancestries. The detection of over 4000 CFTR variants, including several ancestry-specific and uncharacterized CFTR variants, warrants the need for further characterization of their functional and clinical relevance. Overall, the presentation of classical CF phenotypes seen in non-CF diagnosed participants with more than one CF-causing variant indicates that they may benefit from current CFTR modulator therapies. [ABSTRACT FROM AUTHOR]

Epithelial ion and fluid transport studies in patient-derived organoids (PDOs) are increasingly being used for preclinical studies, drug development and precision medicine applications. Epithelial fluid transport properties in PDOs can be measured through visual changes in organoid (lumen) size. Such organoid phenotypes have been highly instrumental for the studying of diseases, including cystic fibrosis (CF), which is characterized by genetic mutations of the CF transmembrane conductance regulator (CFTR) ion channel. Here we present OrgaSegment, a MASK-RCNN based deep-learning segmentation model allowing for the segmentation of individual intestinal PDO structures from bright-field images. OrgaSegment recognizes spherical structures in addition to the oddly-shaped organoids that are a hallmark of CF organoids and can be used in organoid swelling assays, including the new drug-induced swelling assay that we show here. OrgaSegment enabled easy quantification of organoid swelling and could discriminate between organoids with different CFTR mutations, as well as measure responses to CFTR modulating drugs. The easy-to-apply label-free segmentation tool can help to study CFTR-based fluid secretion and possibly other epithelial ion transport mechanisms in organoids. A deep learning model—OrgaSegment—is presented for segmentation of individual intestinal patient-derived organoid structures from bright-field images. This enables quantification of organoid swelling and discrimination between organoids with different levels CFTR function and response to therapy. [ABSTRACT FROM AUTHOR]

The phenomenon of antimicrobial resistance (AMR) is a critical global health challenge, with prospects indicating its potential to become the leading cause of death worldwide in the coming years. Individuals with pre-existing conditions, such as neoplastic disease undergoing chemotherapy, those on immunosuppressive therapy, and individuals with rare diseases like cystic fibrosis (CF), face heightened challenges due to AMR. CF is a rare disease caused by a deficiency in the synthesis of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel protein, resulting in multi-organ clinical symptoms, particularly in the respiratory system. PwCF experience recurrent pulmonary exacerbations triggered by bacterial or viral infections, making them particularly vulnerable to the impact of AMR. This review delves into the complex relationship between AMR and climate dynamics, focusing on the unique challenges faced by individuals with CF. It discusses the methods employed to measure AMR, its global impact on antibiotic resistance, and the specific microbial communities present in the CF airway. The review also explores the intricacies of antimicrobial resistance within the context of cystic fibrosis, emphasizing the urgent need for research in this field. [ABSTRACT FROM AUTHOR]

Cystic fibrosis (CF) is a fatal autosomal recessive disorder caused by the loss of function mutations within a single gene for the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). CFTR is a chloride channel that regulates ion and fluid transport across various epithelia. The discovery of CFTR as the CF gene and its cloning in 1989, coupled with extensive research that went into the understanding of the underlying biological mechanisms of CF, have led to the development of revolutionary therapies in CF that we see today. The highly effective modulator therapies have increased the survival rates of CF patients and shifted the epidemiological landscape and disease prognosis. However, the differential effect of modulators among CF patients and the presence of non-responders and ineligible patients underscore the need to develop specialized and customized therapies for a significant number of patients. Recent advances in the understanding of the CFTR structure, its expression, and defined cellular compositions will aid in developing more precise therapies. As the lifespan of CF patients continues to increase, it is becoming critical to clinically address the extra-pulmonary manifestations of CF disease to improve the quality of life of the patients. In-depth analysis of the molecular signature of different CF organs at the transcriptional and post-transcriptional levels is rapidly advancing and will help address the etiological causes and variability of CF among patients and develop precision medicine in CF. In this review, we will provide an overview of CF disease, leading to the discovery and characterization of CFTR and the development of CFTR modulators. The later sections of the review will delve into the key findings derived from single-molecule and single-cell-level analyses of CFTR, followed by an exploration of disease-relevant protein complexes of CFTR that may ultimately define the etiological course of CF disease. [ABSTRACT FROM AUTHOR]

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel that regulates electrolyte and fluid balance in epithelial tissues. While activation of CFTR is vital to treating cystic fibrosis, selective inhibition of CFTR is a potential therapeutic strategy for secretory diarrhea and autosomal dominant polycystic kidney disease. Although several CFTR inhibitors have been developed by high-throughput screening, their modes of action remain elusive. In this study, we determined the structure of CFTR in complex with the inhibitor CFTRinh-172 to an overall resolution of 2.7 Å by cryogenic electron microscopy. We observe that CFTRinh-172 binds inside the pore near transmembrane helix 8, a critical structural element that links adenosine triphosphate hydrolysis with channel gating. Binding of CFTRinh-172 stabilizes a conformation in which the chloride selectivity filter is collapsed, and the pore is blocked from the extracellular side of the membrane. Single-molecule fluorescence resonance energy transfer experiments indicate that CFTRinh-172 inhibits channel gating without compromising nucleotide-binding domain dimerization. Together, these data reconcile previous biophysical observations and provide a molecular basis for the activity of this widely used CFTR inhibitor. [ABSTRACT FROM AUTHOR]

Chronic intestinal inflammation is a poorly understood manifestation of cystic fibrosis (CF), which may be refractory to ion channel CF transmembrane conductance regulator (CFTR) modulator therapy. People with CF exhibit intestinal dysbiosis, which has the potential for stimulating intestinal and systemic inflammation. CFTR is expressed in organ epithelia, leukocytes, and other tissues. Here, we investigate the contribution of intestinal epithelium-specific loss of Cftr [iCftr knockout (KO)] to dysbiosis and inflammation in mice treated with either of two antiobstructive dietary regimens necessary to maintain CF mouse models [polyethylene glycol (PEG) laxative or a liquid diet (LiqD)]. Feces collected from iCftr KO mice and their wild-type (WT) sex-matched littermates were used to measure fecal calprotectin to evaluate inflammation and to perform 16S rRNA sequencing to characterize the gut microbiome. Fecal calprotectin was elevated in iCftr KO relative to WT mice that consumed either PEG or LiqD. PEG iCftr KO mice did not show a change in α diversity versus WT mice but demonstrated a significant difference in microbial composition (b diversity) with included increases in the phylum Proteobacteria, the family Peptostreptococcaceae, four genera of Clostridia including C. innocuum, and the mucolytic genus Akkermansia. Fecal microbiome analysis of LiqD-fed iCftr KO mice showed both decreased α diversity and differences in microbial composition with increases in the Proteobacteria family Enterobacteriaceae, Firmicutes families Clostridiaceae and Peptostreptococcaceae, and enrichment of Clostridium perfringens, C. innocuum, C. difficile, mucolytic Ruminococcus gnavus, and reduction of Akkermansia. It was concluded that epithelium-specific loss of Cftr is a major driver of CF intestinal dysbiosis and inflammation with significant similarities to previous studies of pan Cftr KO mice. NEW & NOTEWORTHY Chronic intestinal inflammation is a manifestation of cystic fibrosis (CF), a disease caused by loss of the anion channel CF transmembrane conductance regulator (CFTR) that is expressed in many tissues. This study shows that intestinal epithelial cell-specific loss of CFTR [inducible Cftr knockout (KO)] in mice is sufficient to induce intestinal dysbiosis and inflammation. Experiments were performed on mice consuming two dietary regimens routinely used to prevent obstruction in CF mice. [ABSTRACT FROM AUTHOR]

Three distinct pharmacological corrector types (I, II, III) with different binding sites and additive behavior only partially rescue the F508del-cystic fibrosis transmembrane conductance regulator (CFTR) folding and trafficking defect observed in cystic fibrosis. We describe uniquely effective, macrocyclic CFTR correctors that were additive to the known corrector types, exerting a complementary "type IV" corrector mechanism. Macrocycles achieved wild-type-like folding efficiency of F508del-CFTR at the endoplasmic reticulum and normalized CFTR currents in reconstituted patient-derived bronchial epithelium. Using photo-activatable macrocycles, docking studies and site-directed mutagenesis a highly probable binding site and pose for type IV correctors was identified in a cavity between lasso helix-1 (Lh1) and transmembrane helix-1 of membrane spanning domain (MSD)-1, distinct from the known corrector binding sites. Since only F508del-CFTR fragments spanning from Lh1 until MSD2 responded to type IV correctors, these likely promote cotranslational assembly of Lh1, MSD1, and MSD2. Previously corrector-resistant CFTR folding mutants were also robustly rescued, suggesting substantial therapeutic potential for type IV correctors. [ABSTRACT FROM AUTHOR]

This document contains summaries of research studies on respiratory health in children. The studies cover topics such as the impact of certain conditions on hospital admissions, differences in lung function between preterm and term-born individuals, and the effects of air pollution on lung function. Another study evaluates a school-based asthma education program and its positive impact on asthma knowledge and self-management skills in children. These articles provide valuable insights into lung health and can inform future research and clinical practice. [Extracted from the article]

A recent study published in Clinical Otolaryngology evaluated the association between triple combination therapy and the need for endoscopic sinus surgery (ESS) in adult patients with cystic fibrosis (CF) and chronic rhinosinusitis. The study included 128 patients, with 51 receiving triple combination therapy and the remaining patients serving as a control group. The results showed that the group receiving triple combination therapy had a statistically significant reduction in the number of ESS procedures performed compared to the control group. Additionally, the therapy was associated with improvements in sinus CT scores and sinonasal quality of life. However, the study has limitations, and further research is needed to confirm these findings. [Extracted from the article]

Gene therapy holds great potential for treating Lung Cystic Fibrosis (CF) which is a fatal hereditary condition arising from mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in dysfunctional CFTR protein. However, the advancement and clinical application of CF gene therapy systems have been hindered due to the absence of a highly efficient delivery vector. In this work, we introduce a new generation of highly branched poly(β -amino ester) (HPAE) gene delivery vectors for CF treatment. Building upon the classical chemical composition of HPAE, a novel backbone cationization strategy was developed to incorporate additional functional amine groups into HPAE without altering their branching degree. By carefully adjusting the type, proportion, and backbone distribution of the added cationic groups, a series of highly effective HPAE gene delivery vectors were successfully constructed for CF disease gene therapy. In vitro assessment results showed that the backbone cationized HPAEs with randomly distributed 10% proportion of 1-(3-aminopropyl)-4-methylpiperazine (E7) amine groups exhibited superior transfection performance than their counterparts. Furthermore, the top-performed backbone cationized HPAEs, when loaded with therapeutic plasmids, successfully reinstated CFTR protein expression in the CFBE41o- disease model, achieving levels 20–23 times higher than that of normal human bronchial epithelial (HBE) cells. Their therapeutic effectiveness significantly surpassed that of the currently advanced commercial vectors, Xfect and Lipofectamine 3000. [Display omitted] [ABSTRACT FROM AUTHOR]

Cystic fibrosis (CF), an autosomal recessive disease, is caused by variants in both alleles of the CF transmembrane conductance regulator (CFTR) gene. A new assay based on allele-specific polymerase chain reaction and high-resolution melting analysis was developed for the detection of 18 CF-causing CFTR variants previously identified in Cuba and Latin America. The assay is also useful for zygosity determination of mutated alleles and includes internal controls. The reaction mixtures were normalized and evaluated using blood samples collected on filter paper. The evaluation of analytical parameters demonstrated the specificity and sensitivity of the method to detect the included CFTR variants. Internal and external validations yielded a 100% agreement between the new assay and the used reference tests. This assay can complement CF newborn screening not only in Cuba but also in Latin America. [ABSTRACT FROM AUTHOR]

The key role of CFTR in secretory epithelia has been extensively documented. Additionally, CFTR plays a significant role in ion absorption in exocrine glands, including salivary and sweat glands. Most of the knowledge about CFTR expression comes from animal models such as the mouse or the rat, but there is limited information about CFTR expression in human tissues. In the present study, we assessed the expression of CFTR in human submandibular and parotid glands. Consistent with findings in rodent salivary glands, our immunolocalization studies show that CFTR is expressed in duct cells. However, CFTR expression in human salivary glands differs from that in rodents, as immunolocalization and single-cell RNA sequencing analysis from a previous study performed in the human parotid gland revealed the presence of CFTR protein and transcripts within a distinct cell cluster. Based on cell marker expression, this cluster corresponds to acinar cells. To obtain functional evidence supporting CFTR expression, we isolated human parotid acinar cells through collagenase digestion. Acinar cells displayed an anion conductance that was activated in response to cAMP-increasing agents and was effectively blocked by CFTRInh172, a known CFTR blocker. This study provides novel evidence of CFTR expression within acinar cells of human salivary glands. This finding challenges the established model positioning CFTR exclusively in duct cells from exocrine glands. [ABSTRACT FROM AUTHOR]

p.Asn1303Lys (N1303K) is a common missense variant of the CFTR gene, causing cystic fibrosis (CF). In this study, we initially evaluated the influence of CFTR modulators on the restoration of N1303K-CFTR function using intestinal organoids derived from four CF patients expressing the N1303K variant. The forskolin-induced swelling assay in organoids offered valuable insights about the beneficial effects of VX-770 + VX-661 + VX-445 (Elexacaftor + Tezacaftor + Ivacaftor, ETI) on N1303K-CFTR function restoration and about discouraging the prescription of VX-770 + VX-809 (Ivacaftor + Lumacaftor) or VX-770 + VX-661 (Ivacaftor + Tezacaftor) therapy for N1303K/class I patients. Then, a comprehensive assessment was conducted on an example of one patient with the N1303K/class I genotype to examine the ETI effect on the restoration of N1303K-CFTR function using in vitro the patient's intestinal organoids, ex vivo the intestinal current measurements (ICM) method and assessment of the clinical status before and after targeted therapy. All obtained results are consistent with each other and have proven the effectiveness of ETI for the N1303K variant. ETI produced a significant positive effect on forskolin-induced swelling in N1303K/class I organoids indicating functional improvement of the CFTR protein; ICM demonstrated that ETI therapy restored CFTR function in the intestinal epithelium after three months of treatment, and the patient improved his clinical status and lung function, increased his body mass index (BMI) and reduced the lung pathogenic flora diversity, surprisingly without improving the sweat test results. [ABSTRACT FROM AUTHOR]

This review synthesizes articles published in 2023, focusing on the impact of elexacaftor-tezacaftor-ivacaftor (ETI) in cystic fibrosis (CF) care. Real-world data highlights sustained benefits of ETI across age groups, while challenges like neuropsychological side effects persist. Beyond CFTR modulators, research explores telemedicine and novel therapies. Prioritizing equitable access and addressing unmet needs remain crucial for comprehensive CF management. [ABSTRACT FROM AUTHOR]

• The high frequencies of CFTR variants can be explained by a selective advantage for healthy carriers (4–6 % per generation). • Spreading of disease-causing allele carriers was accelerated towards the end of the 18th century. • The most widespread variant (F508del) is estimated to have appeared approximately 190 generations ago. The French region of Brittany presents one of the highest cystic fibrosis (CF)-causing allele frequency in Europe. Here, we tested two hypotheses: i) CF-causing allele carriers arrived by sea in the middle of the 1st millennium AD, and ii) a selective advantage for healthy carriers explains this high rate. From the census of cystic fibrosis patients, frequency maps of the most widespread alleles were established. A mathematical model was developed, based on birth date and place of the ancestors of these patients over 5 centuries, to determine the distribution of local migrations and their parameters for inter-generational intervals of 32 years. This model was applied to simulate the spread of CF-causing variant carriers, according to different scenarios that corresponded to the immigration of a given number of variant carriers at different times (year) and places, and to compare their results to current frequency maps. Migrants carrying a CFTR variant settled in several locations, around which they spread, notably in Central Brittany (F508del variant), Léon (G551D variant) and Cornouaille (1078delT variant). Until the end of the 18th century, the spreading of disease-causing allele carriers was relatively slow, and allele frequencies progressively increased. Then, the mean migration distances increased rapidly, leading to a decline in local frequencies. The main CFTR variants could only have reached their current frequencies through a selective advantage for healthy carriers of the order of 4–6 % at each generation. For the most widespread variant (F508del), the model supports the hypothesis that it appeared around 190 generations ago. [ABSTRACT FROM AUTHOR]

• Lung function and nutrition prior to CFTR modulator therapy was significantly lower in people with CF in south Africa compared to Canada. • Disparities in outcomes are likely due to different socioeconomic conditions, inferior quality of healthcare in SA and early-life determinants of health. • Global disparities in CF outcomes between high and low to middle income countries are likely to widen in future as CFTR modulators rapidly become standard of care in only high-income countries. Outcomes of cystic fibrosis (CF) differ between low-middle income and high-income countries, but comparative data are lacking. We compared South African (SA) and Canadian CF outcomes to explore what disparities existed prior to access of CFTR modulators in Canada. A cross-sectional study of SA and Canadian CF registries data for period 1 January to 31 December 2018. CF registry data were harmonised between countries to compare lung function and nutrition outcomes. Poor nutrition was defined as BMIz-score < -1 in children and < 18.5 kg/m2 in adults. Standardised mean difference (SMD) >10 was considered significant. After excluding Canadians on CFTR modulators and lung transplant recipients, data on 4049 Canadian and 446 SA people was analysed. Compared to Canada, people in SA were younger (median age 15.8 years vs. 24.1 years: SMD 52) with fewer males (47.8% vs 54.2%; SMD 12.5) and White (70.9% vs. 93.3%; SMD 61.3). Class I-III CFTR mutation frequency was similar in SA (n = 384, 86.1%) and Canada (n = 3426, 84.9%). After adjusting for age, gender, diagnosis age, genotype, P.aeruginosa infection and pulmonary treatments, FEV1pp was 8.9% lower (95% CI 6.3% to 11.4%) and poor nutrition 1.7-fold more common (OR 1.70; 95% CI 1.19–2.41) in SA compared to Canada. Lung function and nutrition was significantly lower in SA compared to Canada. Global disparities in CF outcomes between high and low-middle income countries are likely to widen as CFTR modulators are rapidly scaled up in only high-income countries. [ABSTRACT FROM AUTHOR]

• Cystic Fibrosis related chronic rhinosinusitis is common and difficult to treat. • CFTR Modulators improve sinonasal symptoms, imaging and endoscopic appearances. • Current evidence suggests that CFTR modulators do not improve smell threshold. Chronic rhinosinusitis is a common manifestation of CF that is associated with impaired quality of life and can be difficult to treat. CFTR modulator therapy has resulted in significant improvements in lower respiratory and nutritional outcomes for people with CF however their impact on chronic rhinosinusitis has received less attention. We review the literature in relation to chronic rhinosinusitis in CF and examine the impact of CFTR modulator therapy on symptoms, imaging, endoscopic appearances, and olfactory outcomes in the treatment of chronic rhinosinusitis. While an overall improvement in symptoms, imaging and endoscopic appearances is seen in response to treatment, limited impact is documented on olfaction. Outcome measures employed were heterogenous, limiting comparison of findings. There is a need for well powered prospective real-world studies with standardised outcome measures. [ABSTRACT FROM AUTHOR]

This document summarizes a Cochrane review on the use of bisphosphonates for osteoporosis in individuals with cystic fibrosis (CF). The review included nine clinical trials and found that bisphosphonates may increase bone mineral density (BMD) in the spine and hip after 12 months of treatment. However, there was no significant difference in fracture rates between the treatment and control groups. Bisphosphonates may also cause bone pain. The authors concluded that while bisphosphonates may increase BMD in individuals with CF, more research is needed to determine their effectiveness in reducing fractures. Preventive care and collaboration among healthcare professionals are important in managing CF-related bone health. [Extracted from the article]

Objective -- To investigate the effect of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy on physical condition in children with cystic fibrosis (CF) during a 12month period. Materials and Methods -- This is a retrospective cohort study including children aged ≥5 years treated with Elexacaftor/Tezacaftor/Ivacaftor (ELX/TEZ/IVA) or Lumacaftor/ Ivacaftor (LUM/IVA). A six-minute walk test (6MWT) was performed at baseline and at the 3-month follow-ups. Changes in spirometry and sweat chlorides, and body mass index (BMI) were also observed. Collected data were analysed for changes in 6MWT results in correlation with other parameters. The 6MWT results were compared to those predicted for healthy peers. Missing values were replaced using imputation. Results -- Study includes 34 patients (median age 14 years); 28 received ELX/TEZ/ IVA, and 6 LUM/IVA. The average 6MWT walking distance (6MWD) increased from 519.3±107.7 m at baseline to 620.0±99.5 m after 12 months (P<0.0001). The 12 month 6MWD values matched those expected for healthy peers. The increase in BMI z-score (P=0.019) and ppFEV1 (P<0.0001) visible at the 3-month followup was sustained throughout the rest of the year. Sweat chloride concentration decreased (P< 0.0001); after 12 months 13/34 subjects had values below 60 mmol/L. No correlation between 6MWD and other parameters was observed. Conclusion -- Significant improvement in 6MWT results was already visible at three months following the initiation of CFTR modulator treatment. After 12 months patients performed 6MWT at a level indistinguishable from that expected of healthy peers. [ABSTRACT FROM AUTHOR]

Patients with cystic fibrosis (PwCF) have recently experienced an unprecedented breakthrough with the adoption of modulator therapy in clinical practice. This remarkable achievement has led to the reconsideration of disease management as the increased life expectancy has gradually shifted the attention over a spectrum of extra-pulmonary manifestations that become prevalent in the aging population. It comes to be that complementary approaches that target patient co-morbidities are needed for the optimal clinical management of PwCF. A strategy would be to adjuvate the cystic fibrosis transmembrane conductance regulator (CFTR) in performing its functions in the different organs in which it is expressed. Solute carrier family 26 (SLC26) members appear ideal in this context. Indeed, they not only cooperate with CFTR in the organ-dependent regulation of ion fluxes but physically interact with it to reciprocally modulate their function. In this opinion, we summarize available evidence pointing to a physical and functional interaction between CFTR and SLC26 members, with a particular focus on SLC26A6 for its wider expression and broader anion selectivity, and then discuss how restoring the physical interaction between CFTR and SLC26A6 might be beneficial in the treatment of PwCF in the era of modulator therapy. [ABSTRACT FROM AUTHOR]

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that regulates transepithelial salt and fluid homeostasis. CFTR dysfunction leads to reduced chloride secretion into the mucosal lining of epithelial tissues, thereby causing the inherited disease cystic fibrosis. Although several structures of CFTR are available, our understanding of the ion-conduction pathway is incomplete. In particular, the route that connects the cytosolic vestibule with the extracellular space has not been clearly defined, and the structure of the open pore remains elusive. Furthermore, although many residues have been implicated in altering the selectivity of CFTR, the structure of the "selectivity filter" has yet to be determined. In this study, we identify a chloride-binding site at the extracellular ends of transmembrane helices 1, 6, and 8, where a dehydrated chloride is coordinated by residues G103, R334, F337, T338, and Y914. Alterations to this site, consistent with its function as a selectivity filter, affect ion selectivity, conductance, and open channel block. This selectivity filter is accessible from the cytosol through a large inner vestibule and opens to the extracellular solvent through a narrow portal. The identification of a chloride-binding site at the intra- and extracellular bridging point leads us to propose a complete conductance path that permits dehydrated chloride ions to traverse the lipid bilayer. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cystic fibrosis (CF) is a genetic disorder caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), a selective anion channel expressed in the epithelium of various organs. The most frequent mutation is F508del. This mutation leads to a misfolded CFTR protein quickly degraded via ubiquitination in the endoplasmic reticulum. Although preventing ubiquitination stabilizes the protein, functionality is not restored due to impaired plasma membrane transport. However, inhibiting the ubiquitination process can improve the effectiveness of correctors which act as chemical chaperones, facilitating F508del CFTR trafficking to the plasma membrane. Previous studies indicate a crosstalk between SUMOylation and ubiquitination in the regulation of CFTR. In this study, we investigated the potential of inhibiting SUMOylation to increase the effects of correctors and enhance the rescue of the F508del mutant across various cell models. In the widely used CFBE41o-cell line expressing F508del-CFTR, inhibiting SUMOylation substantially boosted F508del expression, thereby increasing the efficacy of correctors. Interestingly, this outcome did not result from enhanced stability of the mutant channel, but rather from augmented cytomegalovirus (CMV) promoter-mediated gene expression of F508del-CFTR. Notably, CFTR regulated by endogenous promoters in multiple cell lines or patient cells was not influenced by SUMOylation inhibitors. [ABSTRACT FROM AUTHOR]