No Sex Differences in Mechanical Thrombectomy Time Metrics and Outcomes in Saskatchewan.

BACKGROUND AND PURPOSE: Numerous studies have shown longer pre-hospital and in-hospital workflow times and poorer outcomes in women after acute ischemic stroke (AIS) in general and after endovascular treatment (EVT) in particular. We investigated sex differences in acute stroke care of EVT patients over 5 years in a comprehensive Canadian provincial registry. METHODS: Clinical data of all AIS patients who underwent EVT between January 2017 and December 2022 in the province of Saskatchewan were captured in the Canadian OPTIMISE registry and supplemented with patient data from administrative data sources. Patient baseline characteristics, transport time metrics, and technical EVT outcomes between female and male EVT patients were compared. RESULTS: Three-hundred-three patients underwent EVT between 2017 and 2022: 144 (47.5%) women and 159 (52.5%) men. Women were significantly older (median age 77.5 [interquartile range: 66-85] vs.71 [59-78], p < 0.001), while men had more intracranial internal carotid artery occlusions (48/159 [30.2%] vs. 26/142 [18.3%], p = 0.03). Last-known-well to comprehensive stroke center (CSC)-arrival time (median 232 min [interquartile range 90-432] in women vs. 230 min [90-352] in men), CSC-arrival-to-reperfusion time (median 108 min [88-149] in women vs. 102 min [77-141] in men), reperfusion status (successful reperfusion 106/142 [74.7%] in women vs. 117/158 [74.1%] in men) as well as modified Rankin score at 90 days did not differ significantly. This held true after adjusting for baseline variables in multivariable analyses. CONCLUSION: While women undergoing EVT in the province of Saskatchewan were on average older than men, they were treated just as fast and achieved similar technical and clinical outcomes compared to men.

Interferon regulatory factor 8 regulates expression of acid ceramidase and infection susceptibility in cystic fibrosis.

Most patients with cystic fibrosis (CF) suffer from acute and chronic pulmonary infections with bacterial pathogens, which often determine their life quality and expectancy. Previous studies have demonstrated a downregulation of the acid ceramidase in CF epithelial cells resulting in an increase of ceramide and a decrease of sphingosine. Sphingosine kills many bacterial pathogens, and the downregulation of sphingosine seems to determine the infection susceptibility of cystic fibrosis mice and patients. It is presently unknown how deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR) connects to a marked downregulation of the acid ceramidase in human and murine CF epithelial cells. Here, we employed quantitative PCR, western blot analysis, and enzyme activity measurements to study the role of IRF8 for acid ceramidase regulation. We report that genetic deficiency or functional inhibition of CFTR/Cftr results in an upregulation of interferon regulatory factor 8 (IRF8) and a concomitant downregulation of acid ceramidase expression with CF and an increase of ceramide and a reduction of sphingosine levels in tracheal and bronchial epithelial cells from both human individuals or mice. CRISPR/Cas9- or siRNA-mediated downregulation of IRF8 prevented changes of acid ceramidase, ceramide, and sphingosine in CF epithelial cells and restored resistance to Pseudomonas aeruginosa infections, which is one of the most important and common pathogens in lung infection of patients with CF. These studies indicate that CFTR deficiency causes a downregulation of acid ceramidase via upregulation of IRF8, which is a central pathway to control infection susceptibility of CF cells.

Clinical and molecular characterization of the R751L-CFTR mutation.

Cystic fibrosis (CF) arises from mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in progressive and life-limiting respiratory disease. R751L is a rare CFTR mutation that is poorly characterized. Our aims were to describe the clinical and molecular phenotypes associated with R751L. Relevant clinical data were collected from three heterozygote individuals harboring R751L (2 patients with G551D/R751L and 1 with F508del/R751L). Assessment of R751L-CFTR function was made in primary human bronchial epithelial cultures (HBEs) and Xenopus oocytes. Molecular properties of R751L-CFTR were investigated in the presence of known CFTR modulators. Although sweat chloride was elevated in all three patients, the clinical phenotype associated with R751L was mild. Chloride secretion in F508del/R751L HBEs was reduced compared with non-CF HBEs and associated with a reduction in sodium absorption by the epithelial sodium channel (ENaC). However, R751L-CFTR function in Xenopus oocytes, together with folding and cell surface transport of R751L-CFTR, was not different from wild-type CFTR. Overall, R751L-CFTR was associated with reduced sodium chloride absorption but had functional properties similar to wild-type CFTR. This is the first report of R751L-CFTR that combines clinical phenotype with characterization of functional and biological properties of the mutant channel. Our work will build upon existing knowledge of mutations within this region of CFTR and, importantly, inform approaches for clinical management. Elevated sweat chloride and reduced chloride secretion in HBEs may be due to alternative non-CFTR factors, which require further investigation.

Recombinant Acid Ceramidase Reduces Inflammation and Infection in Cystic Fibrosis.

Rationale: In cystic fibrosis the major cause of morbidity and mortality is lung disease characterized by inflammation and infection. The influence of sphingolipid metabolism is poorly understood with a lack of studies using human airway model systems.Objectives: To investigate sphingolipid metabolism in cystic fibrosis and the effects of treatment with recombinant human acid ceramidase on inflammation and infection.Methods: Sphingolipids were measured using mass spectrometry in fully differentiated cultures of primary human airway epithelial cells and cocultures with Pseudomonas aeruginosa. In situ activity assays, Western blotting, and quantitative PCR were used to investigate function and expression of ceramidase and sphingomyelinase. Effects of treatment with recombinant human acid ceramidase on sphingolipid profile and inflammatory mediator production were assessed in cell cultures and murine models.Measurements and Main Results: Ceramide is increased in cystic fibrosis airway epithelium owing to differential function of enzymes regulating sphingolipid metabolism. Sphingosine, a metabolite of ceramide with antimicrobial properties, is not upregulated in response to P. aeruginosa by cystic fibrosis airway epithelia. Tumor necrosis factor receptor 1 is increased in cystic fibrosis epithelia and activates NF-κB signaling, generating inflammation. Treatment with recombinant human acid ceramidase, to decrease ceramide, reduced both inflammatory mediator production and susceptibility to infection.Conclusions: Sphingolipid metabolism is altered in airway epithelial cells cultured from people with cystic fibrosis. Treatment with recombinant acid ceramidase ameliorates the two pivotal features of cystic fibrosis lung disease, inflammation and infection, and thus represents a therapeutic approach worthy of further exploration.

Epidemiology of Nontuberculous Mycobacteria Infection in Children and Young People With Cystic Fibrosis: Analysis of UK Cystic Fibrosis Registry.

BACKGROUND: Infection with nontuberculous mycobacteria (NTM) is of growing clinical concern in people with cystic fibrosis (CF). The epidemiology of infection in children and young people remains poorly understood. Our goal was to investigate the epidemiology of NTM infection in the pediatric age group using data from the UK CF Registry. METHODS: Data from 2010-2015 for individuals aged <16 years (23200 observations from 5333 unique individuals) were obtained. Univariate analysis of unique individuals comparing all key clinical factors and health outcomes to NTM status was performed. The significant factors that were identified were used to generate a multivariate logistic regression model that, following step-wise removal, generated a final parsimonious model. RESULTS: The prevalence of individuals with a NTM-positive respiratory culture increased every year from 2010 (45 [1.3%]) to 2015 (156 [3.8%]). Allergic bronchopulmonary aspergillosis (odds ratio [OR], 2.66; P = 5.0 × 10-8), age (OR, 1.08; P = 3.4 × 10-10), and intermittent Pseudomonas aeruginosa infection (OR, 1.51; P = .004) were significantly associated with NTM infection. CONCLUSIONS: NTM infection is of increasing prevalence in the UK pediatric CF population. This study highlights the urgent need for work to establish effective treatment and prevention strategies for NTM infection in young people with CF.

The critical role of TAK1 in accentuated epithelial to mesenchymal transition in obliterative bronchiolitis after lung transplantation.

Therapies to limit or reverse fibrosis have proven unsuccessful, highlighting the need for a greater understanding of basic mechanisms that drive fibrosis and, in particular, the link between fibrosis and inflammation. It has been shown that pro-fibrotic transforming growth factor ß1 (TGF-ß1)-driven epithelial-to-mesenchymal transition (EMT) can be accentuated by tumor necrosis factor α (TNF-α). TGF-ß-activated kinase 1 (TAK1) is activated by both TGF-ß1 and TNF-α, activating both nuclear factor kappa-light-chain-enhancer of activated B cells and mitogen-activated protein kinase signaling pathways. In this study, we evaluated the potential for TAK1 to modulate the synergistic effect between TGF-ß1 and TNF-α in driving EMT. Co-stimulation with TGF-ß1 and TNF-α induced an accentuated and extended phosphorylation of TAK1 compared to either alone. TAK1 signaled downstream via nuclear factor kappa-light-chain-enhancer of activated B cells, and Jun N-terminal kinase-2, but independent of Jun N-terminal kinase-1, extracellular signal-regulated kinase-1/2, or p38 mitogen-activated protein kinase signaling to drive EMT in bronchial epithelial cells. Blocking either TAK1 or Jun N-terminal kinase-2 inhibited EMT. TAK1 phosphorylation was increased in the airway epithelium of patients with fibrotic airway disease. These data identify factors leading to and affected by accentuated and extended TAK1 phosphorylations potential novel therapeutic targets in inflammation-driven fibrotic diseases.

Human hair follicle dermal sheath and papilla cells support keratinocyte growth in monolayer coculture.

Traditional skin grafting techniques are effective but limited methods of skin replacement. Autologous transplantation of rapidly cultured keratinocytes is successful for epidermal regeneration, but the current gold-standard technique requires mouse fibroblast feeders and serum-rich media, with serum-free systems and dermal fibroblast (DF) feeders performing relatively poorly. Here, we investigated the capacity of human hair follicle dermal cells to act as alternative supports for keratinocyte growth. Dermal papilla (DP) dermal sheath (DS), DF and 3T3 cells were used as inactivated feeder cells for human keratinocyte coculture. Under conditions favouring dermal cells, proliferation of keratinocytes in the presence of either DS or DP cells was significantly enhanced compared with DF cells, at levels comparable to keratinocytes cultured under gold-standard conditions. Secreted protein acidic and rich in cysteine (SPARC) expression increased DS and DP cells relative to DFs; however, further experiments did not demonstrate a role in keratinocyte support.

Influence of geography, stroke timing, and weather conditions on transport and workflow times: Results from a longitudinal 5-year Canadian provincial registry.

BACKGROUND: In areas with high population spread such as Saskatchewan, it can be challenging to provide timely endovascular stroke treatment (EVT) to patients living far away from comprehensive stroke centres (CSC). We assessed the association of geography, stroke timing and weather conditions on EVT workflow times and clinical outcomes in Saskatchewan. METHODS: We included patients who underwent EVT between January 2017 and December 2022 in the province of Saskatchewan, Canada. Univariable and multivariable associations of time from last known well-to-CSC arrival, CSC arrival-to-reperfusion, and 90-day modified Rankin Score (mRS) with driving distance from patient home to CSC, transport mode, outdoor temperature and stroke timing (day & time) were assessed using descriptive statistics and multivariable regression. RESULTS: Three-hundred-three patients in the province of Saskatchewan underwent EVT between January 2017 and December 2022. Distance from patient home to CSC (beta-coefficient per 10 km increase = 0.02, 95% CI: 0.01-0.03) and direct to CSC transport (beta-coefficient = -0.76, 95% CI = -1.01-[-0.51]) were associated with last known well to CSC arrival time. In-hospital stroke (beta-coefficient = 0.37, 95% CI: 0.16-0.58), direct-to-CSC transfer (beta-coefficient = 0.27, 95% CI: 0.13-0.41) and daytime stroke onset (beta-coefficient = -0.15, 95% CI: -0.28-[-0.04]) were associated with time from CSC arrival to reperfusion. No association with 90-day mRS was seen. CONCLUSION: Geographic factors and stroke timing were associated with EVT workflow times. However, no association with clinical outcomes was seen, suggesting that EVT patients living remote areas of Saskatchewan have similar benefit from EVT compared to urban areas. Every effort should be made to offer timely EVT to patients from remote areas.

Tissue factor expression in monocyte subsets during human immunothrombosis, endotoxemia and sepsis.

INTRODUCTION: Tissue factor expression on monocytes is implicated in the pathophysiology of sepsis-induced coagulopathy. How tissue factor is expressed by monocyte subsets (classical, intermediate and non-classical) is unknown. METHODS: Monocytic tissue factor surface expression was investigated during three conditions. Primary human monocytes and microvascular endothelial cell co-cultures were used for in vitro studies. Volunteers received a bolus of lipopolysaccharide (2 ng/kg) to induce endotoxemia. Patients with sepsis, or controls with critical illness unrelated to sepsis, were recruited from four intensive care units. RESULTS: Contact with endothelium and stimulation with lipopolysaccharide reduced the proportion of intermediate monocytes. Lipopolysaccharide increased tissue factor surface expression on classical and non-classical monocytes. Endotoxemia induced profound, transient monocytopenia, along with activation of coagulation pathways. In the remaining circulating monocytes, tissue factor was up-regulated in intermediate monocytes, though approximately 60 % of individuals (responders) up-regulated tissue factor across all monocyte subsets. In critically ill patients, tissue factor expression on intermediate and non-classical monocytes was significantly higher in patients with established sepsis than among non-septic patients. Upon recovery of sepsis, expression of tissue factor increased significantly in classical monocytes. CONCLUSION: Tissue factor expression in monocyte subsets varies significantly during health, endotoxemia and sepsis.

Evaluating the Immune Response in Treatment-Naive Hospitalised Patients With Influenza and COVID-19.

The worldwide COVID-19 pandemic has claimed millions of lives and has had a profound effect on global life. Understanding the body's immune response to SARS-CoV-2 infection is crucial in improving patient management and prognosis. In this study we compared influenza and SARS-CoV-2 infected patient cohorts to identify distinct blood transcript abundances and cellular composition to better understand the natural immune response associated with COVID-19, compared to another viral infection being influenza, and identify a prognostic signature of COVID-19 patient outcome. Clinical characteristics and peripheral blood were acquired upon hospital admission from two well characterised cohorts, a cohort of 88 patients infected with influenza and a cohort of 80 patients infected with SARS-CoV-2 during the first wave of the pandemic and prior to availability of COVID-19 treatments and vaccines. Gene transcript abundances, enriched pathways and cellular composition were compared between cohorts using RNA-seq. A genetic signature between COVID-19 survivors and non-survivors was assessed as a prognostic predictor of COVID-19 outcome. Contrasting immune responses were detected with an innate response elevated in influenza and an adaptive response elevated in COVID-19. Additionally ribosomal, mitochondrial oxidative stress and interferon signalling pathways differentiated the cohorts. An adaptive immune response was associated with COVID-19 survival, while an inflammatory response predicted death. A prognostic transcript signature, associated with circulating immunoglobulins, nucleosome assembly, cytokine production and T cell activation, was able to stratify COVID-19 patients likely to survive or die. This study provides a unique insight into the immune responses of treatment naïve patients with influenza or COVID-19. The comparison of immune response between COVID-19 survivors and non-survivors enables prognostication of COVID-19 patients and may suggest potential therapeutic strategies to improve survival.

Blood gene expression predicts intensive care unit admission in hospitalised patients with COVID-19.

Background: The COVID-19 pandemic has created pressure on healthcare systems worldwide. Tools that can stratify individuals according to prognosis could allow for more efficient allocation of healthcare resources and thus improved patient outcomes. It is currently unclear if blood gene expression signatures derived from patients at the point of admission to hospital could provide useful prognostic information. Methods: Gene expression of whole blood obtained at the point of admission from a cohort of 78 patients hospitalised with COVID-19 during the first wave was measured by high resolution RNA sequencing. Gene signatures predictive of admission to Intensive Care Unit were identified and tested using machine learning and topological data analysis, TopMD. Results: The best gene expression signature predictive of ICU admission was defined using topological data analysis with an accuracy: 0.72 and ROC AUC: 0.76. The gene signature was primarily based on differentially activated pathways controlling epidermal growth factor receptor (EGFR) presentation, Peroxisome proliferator-activated receptor alpha (PPAR-α) signalling and Transforming growth factor beta (TGF-ß) signalling. Conclusions: Gene expression signatures from blood taken at the point of admission to hospital predicted ICU admission of treatment naïve patients with COVID-19.

Trends in nontuberculous mycobacteria infection in children and young people with cystic fibrosis.

Nontuberculous mycobacteria (NTM) infection is of growing concern in cystic fibrosis (CF). UK CF Registry data were analyzed from 2016 to 2018. Prevalence of infection stabilized in the pediatric age-group during this period but remained substantially higher than in 2010. Allergic bronchopulmonary aspergillosis and Pseudomonas aeruginosa infection were associated with NTM infection.

Delayed induction of type I and III interferons mediates nasal epithelial cell permissiveness to SARS-CoV-2.

The nasal epithelium is a plausible entry point for SARS-CoV-2, a site of pathogenesis and transmission, and may initiate the host response to SARS-CoV-2. Antiviral interferon (IFN) responses are critical to outcome of SARS-CoV-2. Yet little is known about the interaction between SARS-CoV-2 and innate immunity in this tissue. Here we apply single-cell RNA sequencing and proteomics to a primary cell model of human nasal epithelium differentiated at air-liquid interface. SARS-CoV-2 demonstrates widespread tropism for nasal epithelial cell types. The host response is dominated by type I and III IFNs and interferon-stimulated gene products. This response is notably delayed in onset relative to viral gene expression and compared to other respiratory viruses. Nevertheless, once established, the paracrine IFN response begins to impact on SARS-CoV-2 replication. When provided prior to infection, recombinant IFNß or IFNλ1 induces an efficient antiviral state that potently restricts SARS-CoV-2 viral replication, preserving epithelial barrier integrity. These data imply that the IFN-I/III response to SARS-CoV-2 initiates in the nasal airway and suggest nasal delivery of recombinant IFNs to be a potential chemoprophylactic strategy.

Transgender and Gender Nonconforming Patient Experience in the Inland Empire, California.

Analyzing secondary data from a 2015 survey of 90 transgender and gender nonconforming individuals in California's Inland Empire, this study reports frequencies of physical and mental health and health care access and discrimination outcomes and differences by age, race/ethnicity, and sex assigned at birth. Nearly three-quarters of respondents reported positive physical health, yet only about half reported positive mental health-an outcome poorer for respondents <50 years. Lesser than 50% found it very easy to find providers for routine care and only 16% found it very easy to find a transgender-competent provider, underscoring the need for more health professional training.

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells.

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) hydration, mucus viscosity and activity of antimicrobial peptides, key parameters involved in innate defense of the lungs. This is of primary relevance in the field of chronic respiratory diseases such as cystic fibrosis (CF) where these parameters are dysregulated. While different groups have studied ASL pH both in vivo and in vitro, their methods report a relatively wide range of ASL pH values and even contradictory findings regarding any pH differences between non-CF and CF cells. Furthermore, their protocols do not always provide enough details in order to ensure reproducibility, most are low throughput and require expensive equipment or specialized knowledge to implement, making them difficult to establish in most labs. Here we describe a semi-automated fluorescent plate reader assay that enables the real-time measurement of ASL pH under thin film conditions that more closely resemble the in vivo situation. This technique allows for stable measurements for many hours from multiple airway cultures simultaneously and, importantly, dynamic changes in ASL pH in response to agonists and inhibitors can be monitored. To achieve this, the ASL of fully differentiated primary human airway epithelial cells (hAECs) are stained overnight with a pH-sensitive dye in order to allow for the reabsorption of the excess fluid to ensure thin film conditions. After fluorescence is monitored in the presence or absence of agonists, pH calibration is performed in situ to correct for volume and dye concentration. The method described provides the required controls to make stable and reproducible ASL pH measurements, which ultimately could be used as a drug discovery platform for personalized medicine, as well as adapted to other epithelial tissues and experimental conditions, such as inflammatory and/or host-pathogen models.

Extending the Reach of Pediatric Emergency Preparedness: A Virtual Tabletop Exercise Targeting Children's Needs.

OBJECTIVES: Virtual tabletop exercises (VTTXs) simulate disaster scenarios to help participants improve their emergency-planning capacity. The objectives of our study were to (1) evaluate the effectiveness of a VTTX in improving preparedness capabilities specific to children's needs among pediatricians and public health practitioners, (2) document follow-up actions, and (3) identify exercise strengths and weaknesses. METHODS: In February 2017, we conducted and evaluated a VTTX facilitated via videoconferencing among 26 pediatricians and public health practitioners from 4 states. Using a mixed-methods design, we assessed participants' knowledge and confidence to fulfill targeted federal preparedness capabilities immediately before and after the exercise. We also evaluated the degree to which participants made progress on actions through surveys 1 month (n = 14) and 6 months (n = 14) after the exercise. RESULTS: Participants reported a greater ability to identify their state's pediatric emergency preparedness strengths and weaknesses after the exercise (16 of 18) compared with before the exercise (10 of 18). We also observed increases in (1) knowledge of and confidence in performing most pediatric emergency preparedness capabilities and (2) most dimensions of interprofessional collaboration. From 1 month to 6 months after the exercise, participants (n = 14) self-reported making progress in increasing awareness for potential preparedness partners and in conducting similar pediatric exercises (from 4-7 for both). CONCLUSIONS: Participants viewed the VTTX positively and indicated increased pediatric emergency preparedness knowledge and confidence. Addressing barriers to improving local pediatric emergency preparedness-particularly long term-is an important target for future tabletop exercises.

Medical Countermeasures for Children in Radiation and Nuclear Disasters: Current Capabilities and Key Gaps.

OBJECTIVE: Despite children's unique vulnerability, clinical guidance and resources are lacking around the use of radiation medical countermeasures (MCMs) available commercially and in the Strategic National Stockpile to support immediate dispensing to pediatric populations. To better understand the current capabilities and shortfalls, a literature review and gap analysis were performed. METHODS: A comprehensive review of the medical literature, Food and Drug Administration (FDA)-approved labeling, FDA summary reviews, medical references, and educational resources related to pediatric radiation MCMs was performed from May 2016 to February 2017. RESULTS: Fifteen gaps related to the use of radiation MCMs in children were identified. The need to address these gaps was prioritized based upon the potential to decrease morbidity and mortality, improve clinical management, strengthen caregiver education, and increase the relevant evidence base. CONCLUSIONS: Key gaps exist in information to support the safe and successful use of MCMs in children during radiation emergencies; failure to address these gaps could have negative consequences for families and communities. There is a clear need for pediatric-specific guidance to ensure clinicians can appropriately identify, triage, and treat children who have been exposed to radiation, and for resources to ensure accurate communication about the safety and utility of radiation MCMs for children. (Disaster Med Public Health Preparedness. 2019;13:639-646).

Addressing Children's Needs in Disasters: A Regional Pediatric Tabletop Exercise.

OBJECTIVE: Preparing and responding to the needs of children during public health emergencies continues to be challenging. The purpose of this study was to assess the usefulness of a tabletop exercise in initiating pediatric preparedness strategies and assessing the impact of the exercise on participants' understanding of and confidence in their roles during pediatric public health emergencies. METHODS: A tabletop exercise was developed to simulate a public health emergency scenario involving smallpox in a child, with subsequent spread to multiple states. During the exercise, participants discussed and developed communication, collaboration, and medical countermeasure strategies to enhance pediatric public health preparedness. Exercise evaluation was designed to assess participants' knowledge gained and level of confidence surrounding pediatric public health emergencies. RESULTS: In total, 22 participants identified over 100 communication and collaboration strategies to promote pediatric public health preparedness during the exercise and found that the most beneficial aspect during the exercise was the partnership between pediatricians and public health officials. Participants' knowledge and level of confidence surrounding a pediatric public health emergency increased after the exercise. CONCLUSION: The tabletop exercise was effective in identifying strategies to improve pediatric public health preparedness as well as enhancing participants' knowledge and confidence surrounding a potential pediatric public health emergency. (Disaster Med Public Health Preparedness. 2018;12:582-586).

Sphingolipids as targets for inhalation treatment of cystic fibrosis.

Studies over the past several years have demonstrated the important role of sphingolipids in cystic fibrosis (CF), chronic obstructive pulmonary disease and acute lung injury. Ceramide is increased in airway epithelial cells and alveolar macrophages of CF mice and humans, while sphingosine is dramatically decreased. This increase in ceramide results in chronic inflammation, increased death of epithelial cells, release of DNA into the bronchial lumen and thereby an impairment of mucociliary clearance; while the lack of sphingosine in airway epithelial cells causes high infection susceptibility in CF mice and possibly patients. The increase in ceramide mediates an ectopic expression of ß1-integrins in the luminal membrane of CF epithelial cells, which results, via an unknown mechanism, in a down-regulation of acid ceramidase. It is predominantly this down-regulation of acid ceramidase that results in the imbalance of ceramide and sphingosine in CF cells. Correction of ceramide and sphingosine levels can be achieved by inhalation of functional acid sphingomyelinase inhibitors, recombinant acid ceramidase or by normalization of ß1-integrin expression and subsequent re-expression of endogenous acid ceramidase. These treatments correct pulmonary inflammation and prevent or treat, respectively, acute and chronic pulmonary infections in CF mice with Staphylococcus aureus and mucoid or non-mucoid Pseudomonas aeruginosa. Inhalation of sphingosine corrects sphingosine levels only and seems to mainly act against the infection. Many antidepressants are functional inhibitors of the acid sphingomyelinase and were designed for systemic treatment of major depression. These drugs could be repurposed to treat CF by inhalation.

Ataluren in cystic fibrosis: development, clinical studies and where are we now?

INTRODUCTION: Cystic fibrosis (CF) is one of the most common genetically-acquired life-limiting conditions worldwide. The underlying defect is dysfunction of the cystic fibrosis transmembrane-conductance regulator (CFTR) which leads to progressive lung disease and other multi-system effects. Around 10% of people with CF have a class I nonsense mutation that leads to production of shortened CFTR due to a premature termination codon (PTC). Areas covered: We discuss the discovery of the small-molecule drug ataluren, which in vitro has been shown to allow read-through of PTCs and facilitate synthesis of full-length protein. We review clinical studies that have been performed involving ataluren in CF. Early-phase short-term cross-over studies showed improvement in nasal potential difference. A follow-up phase III randomised controlled trial did not show a significant difference for the primary outcome of lung function, however a post-hoc analysis suggested possible benefit in patients not receiving tobramycin. A further randomised controlled trial in patients not receiving tobramycin has been reported as showing no benefit but has not yet been published in full peer-reviewed form. Expert opinion: A small-molecule approach to facilitate read-through of PTCs in nonsense mutations makes intuitive sense. However, at present there is no high-quality evidence of clinical efficacy for ataluren in people with CF.