Inhaled medications in cystic fibrosis beyond antibiotics.

Minerva Pediatr. 2019 Feb 13;:

Authors: Sepe A, Villella VR, Cimbalo C, Castaldo A, Nunziata F, Corcione A, Bona G, Maiuri L, Raia V

Abstract
Structural lung disease begins very early in children with Cystic Fibrosis, often in the first three months of life. Inhaled medications represent an attractive therapeutic approach in Cystic Fibrosis that are routinely used as early intervention strategies. Two aerosolized solutions, hypertonic saline and dornase alfa, have significant potential benefits by improving mucociliary clearance, with minimal associated side-effects. In particular, they favor rehydration of airway surface liquid and cleavage of extracellular DNA in the airways, respectively, consequently reducing rate of pulmonary disease exacerbations. Indirect anti-inflammatory effects have been documented for both drugs, addressing each of the three interrelated elements in the vicious cycle of lung disease in CF: airway obstruction, inflammation and infection. This short review aims to summarize the main papers that support potential clinical impact of inhaled solutions on pulmonary disease in CF.

PMID: 30761821 [PubMed - as supplied by publisher]

Mutation-specific therapies and drug repositioning in cystic fibrosis.

Minerva Pediatr. 2019 Feb 13;:

Authors: Villella VR, Tosco A, Esposito S, Bona G, Raia V, Maiuri L

Abstract
Cystic Fibrosis (CF) is an inherited, prematurely lethal rare disease affecting more than 85,000 people worldwide. CF is caused by more than 2000 loss-of-function mutations in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR). This review summarizes recent advances in the etiological therapies of CF that aim at repairing the functional defect of CFTR by means of CFTR modulators. We will discuss the state of art of the mutation-specific treatments that are designed to target different steps of the CFTR biogenesis perturbed by mutations in CFTR gene. Moreover, we will discuss how drug repositioning, namely the use of drugs already approved for the treatment of other human diseases, may be repurposed in CF patients to circumvent CFTR dysfunction. Finally, we highlight how the combined use of two o more compounds acting on different disease mechanisms is required to achieve clinical benefit in CF population.

PMID: 30761820 [PubMed - as supplied by publisher]

Characteristics of CF-related Diabetes: Data from Two Different Sources the ECFS Patient Registry and the DPV Registry.

Pediatr Diabetes. 2019 Feb 13;:

Authors: Prinz N, Zolin A, Konrad K, Nährlich L, Laubner K, Olesen HV, Bauer M, Jung A, Frischer T, Holl RW, ECFS patient registry and the DPV registry

Abstract
BACKGROUND: Standardized patient registries provide a unique basis to get insight into cystic fibrosis-related diabetes (CFRD), the most common comorbidity in cystic fibrosis.
METHODS: 3,853 CFRD patients from the European CF Society Patient Registry (ECFSPR) and 752 from the German/Austrian diabetes prospective follow-up (DPV) were studied. To adjust for age and sex, multivariable regression was used (SAS 9.4).
RESULTS: DPV subjects were younger (26.5 [20.2-32.6] vs. 28.3 [21.7-36.0] years, p<0.001) and more often female (59.6 vs. 50.9%, p<0.001). In both registries, F508del homozygotes were most frequent, with higher proportion in DPV (80.9 vs. 57.8%, p=0.003). After adjustment, lung-transplantation (LTX) was more common in ECFSPR (18.9 vs. 4.9%, p<0.001), although duration since LTX (4.8&pm;0.2 vs. 5.5&pm;0.7 years, p=0.33) did not differ. In DPV patients without LTX, a lower BMI (19.6&pm;0.1 vs. 21.0&pm;0.1 kg/m2 , p<0.001), higher proportion of underweight (41.2 vs. 20.2%, p<0.001) and a tendency towards worse lung function (%FEV1 : 42.3&pm;4.2 vs. 48.3&pm;0.5%, p=0.16) were observed.
CONCLUSIONS: Between both registries, demographic and clinical differences of CFRD were present. Besides different kind of data sources, diverse treatment structures between countries may play a role. The results may further indicate a more serious illness in patients treated in specialized diabetes clinics, documenting their data in DPV. This article is protected by copyright. All rights reserved.

PMID: 30761696 [PubMed - as supplied by publisher]

Longitudinal assessment of exercise capacity and quality of life outcome measures in cystic fibrosis: A year-long prospective pilot study.

J Eval Clin Pract. 2019 Feb 13;:

Authors: Bhatia R, Kaye M, Roberti-Miller A

Abstract
BACKGROUND: Multiple outcomes measures including exercise capacity and quality of life are necessary to get complete and accurate picture of cystic fibrosis (CF) progression. In this pilot study, we investigated these measures in CF longitudinally for a year to determine (a) minimal clinically important difference (MCID) for 6-minute walk distance (6MWD) and CF Health-Related Quality of Life Questionnaire (CFQ-R) domains and (b) how 6MWD, CFQ-R, and spirometry change during times of exacerbation and baseline health and their relationship among each other.
METHODS: Subjects with moderate and severe CF (baseline FEV1 less than 70% predicted) at Akron Children's Hospital CF centre were followed for a full year longitudinally. All three tests (6MWT, CFQ-R, and spirometry) were done during each outpatient visit and weekly during inpatient admission. MCID was estimated for these parameters using distribution-based methods. Finally, data were examined visually using longitudinal graphs for each subject.
RESULTS: Twelve CF subjects (eight [67%] males and age range 13-46 years) were followed for a full year resulting in at least four encounters per subject. 6MWD (m) and CFQ-R respiratory had an MCID of 33 m and 7.3, respectively. MCIDs for FEV1 (percentage predicted) and CFQ-R physical were 7.1 and 11.4, respectively. The longitudinal evaluation of multiple outcome measures during periods of disease exacerbation and baseline health showed that these parameters did not appear to change in accordance with each other.
CONCLUSION: In this pilot study, MCIDs for 6MWD and CFQ-R domains were calculated for the first time to facilitate their use as additional outcome measures in CF. The disparity among multiple outcome measures highlights that these measures together may provide a more complete picture in CF than any single measure alone.

PMID: 30761692 [PubMed - as supplied by publisher]

Cystic fibrosis - an example of personalized and precision medicine.

APMIS. 2019 Feb 14;:

Authors: Skov M, Hansen CR, Pressler T

Abstract
Cystic fibrosis (CF) is a severe, monogenic, autosomal recessive disease caused by mutations in the CFTR (cystic fibrosis transmembrane regulator) gene, where disturbed chloride and bicarbonate transportation in epithelial cells results in a multiorgan disease with primarily pulmonary infections and pancreatic insufficiency. In 1968, the Copenhagen CF Center was established, and centralized care of CF patients with monthly control was introduced. Close monitoring and treatment of Pseudomonas lung infection as well as segregation of patients with different infection status improved the clinical outcome as well as survival. Prophylactic basic treatment as well as infection treatments follow specific algorithms. A variety of comorbidities have all along the pulmonary infection control necessitated personalized care, adjusted to the patients' phenotype. With the introduction of CFTR modulators, the treatment has shifted from prophylactic, symptomatic type toward a new era of precision medicine targeting the basic defect according to the patients' CFTR genotype. Future directions will focus on further improvement of the CFTR modulators and gene therapy, as well as modifier genes and CF phenotype.

PMID: 30761610 [PubMed - as supplied by publisher]

Clinical impact and cost-effectiveness of a 176-condition expanded carrier screen.

Genet Med. 2019 Feb 14;:

Authors: Beauchamp KA, Johansen Taber KA, Muzzey D

Abstract
PURPOSE: Carrier screening identifies couples at high risk for conceiving offspring affected with serious heritable conditions. Minimal guidelines recommend offering testing for cystic fibrosis and spinal muscular atrophy, but expanded carrier screening (ECS) assesses hundreds of conditions simultaneously. Although medical societies consider ECS an acceptable practice, the health economics of ECS remain incompletely characterized.
METHODS: Preconception screening was modeled using a decision tree comparing minimal screening and a 176-condition ECS panel. Carrier rates from >60,000 patients, primarily with private insurance, informed disease incidence estimates, while cost and life-years-lost data were aggregated from the literature and a cost-of-care database. Model robustness was evaluated using one-way and probabilistic sensitivity analyses.
RESULTS: For every 100,000 pregnancies, 290 are predicted to be affected by ECS-panel conditions, which, on average, increase mortality by 26 undiscounted life-years and individually incur $1,100,000 in lifetime costs. Relative to minimal screening, preconception ECS reduces the affected birth rate and is estimated to be cost-effective (i.e.,<$50,000 incremental cost per life-year), findings robust to perturbation.
CONCLUSION: Based on screened patients predominantly with private coverage, preconception ECS is predicted to reduce the burden of Mendelian disease in a cost-effective manner compared with minimal screening. The data and framework herein may facilitate similar assessments in other cohorts.

PMID: 30760891 [PubMed - as supplied by publisher]

Synthesis and antibiotic activity of novel acylated phloroglucinol compounds against methicillin-resistant Staphylococcus aureus.

J Antibiot (Tokyo). 2019 Feb 13;:

Authors: Mittal N, Tesfu HH, Hogan AM, Cardona ST, Sorensen JL

Abstract
The rise in antibiotic resistance among pathogenic microorganisms has created an imbalance in the drugs available for treatment, in part due to the slow development of new antibiotics. Cystic fibrosis (CF) patients are highly susceptible to antibiotic-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Phloroglucinols and related polyketide natural products have demonstrated antimicrobial activity against a number of Gram-positive bacteria including S. aureus. In this study, we investigated a series of acylated phloroglucinol derivatives to determine their potential as lead compounds for the design of novel therapeutics. To assess the activity of these compounds, we determined the minimum inhibitory and bactericidal concentration (MIC and MBC, respectively), the minimum biofilm inhibitory and biofilm eradication concentration (MBIC and MBEC, respectively), and evaluated hemolytic activity, as well as their interaction with clinically relevant antibiotics. Of the 12 compounds tested against MRSA and methicillin-susceptible strains, four showed MIC values ranging from 0.125 to 8 µg ml-1 and all of them were bactericidal. However, none of the compounds were able to eradicate biofilms at the concentrations tested. Three of the four did not display hemolytic activity under the conditions tested. Further studies on the interactions of these compounds with clinically relevant antibiotics showed that phlorodipropanophenone displayed synergistic activity when paired with doxycycline. Our results suggest that these acylated phloroglucinols have potential for being further investigated as antibacterial leads.

PMID: 30760838 [PubMed - as supplied by publisher]

Neutrophilic proteolysis in the cystic fibrosis lung correlates with a pathogenic microbiome.

Microbiome. 2019 Feb 13;7(1):23

Authors: Quinn RA, Adem S, Mills RH, Comstock W, DeRight Goldasich L, Humphrey G, Aksenov AA, Melnik AV, da Silva R, Ackermann G, Bandeira N, Gonzalez DJ, Conrad D, O'Donoghue AJ, Knight R, Dorrestein PC

Abstract
BACKGROUND: Studies of the cystic fibrosis (CF) lung microbiome have consistently shown that lung function decline is associated with decreased microbial diversity due to the dominance of opportunistic pathogens. However, how this phenomenon is reflected in the metabolites and chemical environment of lung secretions remains poorly understood.
METHODS: Here we investigated the microbial and molecular composition of CF sputum samples using 16S rRNA gene amplicon sequencing and untargeted tandem mass spectrometry to determine their interrelationships and associations with clinical measures of disease severity.
RESULTS: The CF metabolome was found to exist in two states: one from patients with more severe disease that had higher molecular diversity and more Pseudomonas aeruginosa and the other from patients with better lung function having lower metabolite diversity and fewer pathogenic bacteria. The two molecular states were differentiated by the abundance and diversity of peptides and amino acids. Patients with severe disease and more pathogenic bacteria had higher levels of peptides. Analysis of the carboxyl terminal residues of these peptides indicated that neutrophil elastase and cathepsin G were responsible for their generation, and accordingly, these patients had higher levels of proteolytic activity from these enzymes in their sputum. The CF pathogen Pseudomonas aeruginosa was correlated with the abundance of amino acids and is known to primarily feed on them in the lung.
CONCLUSIONS: In cases of severe CF lung disease, proteolysis by host enzymes creates an amino acid-rich environment that P. aeruginosa comes to dominate, which may contribute to the pathogen's persistence by providing its preferred carbon source.

PMID: 30760325 [PubMed - in process]

Mimicry and well known genetic friends: molecular diagnosis in an Iranian cohort of suspected Bartter syndrome and proposition of an algorithm for clinical differential diagnosis.

Orphanet J Rare Dis. 2019 Feb 13;14(1):41

Authors: Najafi M, Kordi-Tamandani DM, Behjati F, Sadeghi-Bojd S, Bakey Z, Karimiani EG, Schüle I, Azarfar A, Schmidts M

Abstract
BACKGROUND: Bartter Syndrome is a rare, genetically heterogeneous, mainly autosomal recessively inherited condition characterized by hypochloremic hypokalemic metabolic alkalosis. Mutations in several genes encoding for ion channels localizing to the renal tubules including SLC12A1, KCNJ1, BSND, CLCNKA, CLCNKB, MAGED2 and CASR have been identified as underlying molecular cause. No genetically defined cases have been described in the Iranian population to date. Like for other rare genetic disorders, implementation of Next Generation Sequencing (NGS) technologies has greatly facilitated genetic diagnostics and counseling over the last years. In this study, we describe the clinical, biochemical and genetic characteristics of patients from 15 Iranian families with a clinical diagnosis of Bartter Syndrome.
RESULTS: Age range of patients included in this study was 3 months to 6 years and all patients showed hypokalemic metabolic alkalosis. 3 patients additionally displayed hypercalciuria, with evidence of nephrocalcinosis in one case. Screening by Whole Exome Sequencing (WES) and long range PCR revealed that 12/17 patients (70%) had a deletion of the entire CLCNKB gene that was previously identified as the most common cause of Bartter Syndrome in other populations. 4/17 individuals (approximately 25% of cases) were found to suffer in fact from pseudo-Bartter syndrome resulting from congenital chloride diarrhea due to a novel homozygous mutation in the SLC26A3 gene, Pendred syndrome due to a known homozygous mutation in SLC26A4, Cystic Fibrosis (CF) due to a novel mutation in CFTR and apparent mineralocorticoid excess syndrome due to a novel homozygous loss of function mutation in HSD11B2 gene. 1 case (5%) remained unsolved.
CONCLUSIONS: Our findings demonstrate deletion of CLCNKB is the most common cause of Bartter syndrome in Iranian patients and we show that age of onset of clinical symptoms as well as clinical features amongst those patients are variable. Further, using WES we were able to prove that nearly 1/4 patients in fact suffered from Pseudo-Bartter Syndrome, reversing the initial clinical diagnosis with important impact on the subsequent treatment and clinical follow up pathway. Finally, we propose an algorithm for clinical differential diagnosis of Bartter Syndrome.

PMID: 30760291 [PubMed - in process]

PyMINEr Finds Gene and Autocrine-Paracrine Networks from Human Islet scRNA-Seq.

Cell Rep. 2019 Feb 12;26(7):1951-1964.e8

Authors: Tyler SR, Rotti PG, Sun X, Yi Y, Xie W, Winter MC, Flamme-Wiese MJ, Tucker BA, Mullins RF, Norris AW, Engelhardt JF

Abstract
Toolsets available for in-depth analysis of scRNA-seq datasets by biologists with little informatics experience is limited. Here, we describe an informatics tool (PyMINEr) that fully automates cell type identification, cell type-specific pathway analyses, graph theory-based analysis of gene regulation, and detection of autocrine-paracrine signaling networks in silico. We applied PyMINEr to interrogate human pancreatic islet scRNA-seq datasets and discovered several features of co-expression graphs, including concordance of scRNA-seq-graph structure with both protein-protein interactions and 3D genomic architecture, association of high-connectivity and low-expression genes with cell type enrichment, and potential for the graph structure to clarify potential etiologies of enigmatic disease-associated variants. We further created a consensus co-expression network and autocrine-paracrine signaling networks within and across islet cell types from seven datasets. PyMINEr correctly identified changes in BMP-WNT signaling associated with cystic fibrosis pancreatic acinar cell loss. This proof-of-principle study demonstrates that the PyMINEr framework will be a valuable resource for scRNA-seq analyses.

PMID: 30759402 [PubMed - in process]

CFTR Protects against Mycobacterium abscessus Infection by Fine-Tuning Host Oxidative Defenses.

Cell Rep. 2019 Feb 12;26(7):1828-1840.e4

Authors: Bernut A, Dupont C, Ogryzko NV, Neyret A, Herrmann JL, Floto RA, Renshaw SA, Kremer L

Abstract
Infection by rapidly growing Mycobacterium abscessus is increasingly prevalent in cystic fibrosis (CF), a genetic disease caused by a defective CF transmembrane conductance regulator (CFTR). However, the potential link between a dysfunctional CFTR and vulnerability to M. abscessus infection remains unknown. Herein, we exploit a CFTR-depleted zebrafish model, recapitulating CF immuno-pathogenesis, to study the contribution of CFTR in innate immunity against M. abscessus infection. Loss of CFTR increases susceptibility to infection through impaired NADPH oxidase-dependent restriction of intracellular growth and reduced neutrophil chemotaxis, which together compromise granuloma formation and integrity. As a consequence, extracellular multiplication of M. abscessus expands rapidly, inducing abscess formation and causing lethal infections. Because these phenotypes are not observed with other mycobacteria, our findings highlight the crucial and specific role of CFTR in the immune control of M. abscessus by mounting effective oxidative responses.

PMID: 30759393 [PubMed - in process]

Rectal Organoids Enable Personalized Treatment of Cystic Fibrosis.

Cell Rep. 2019 Feb 12;26(7):1701-1708.e3

Authors: Berkers G, van Mourik P, Vonk AM, Kruisselbrink E, Dekkers JF, de Winter-de Groot KM, Arets HGM, Marck-van der Wilt REP, Dijkema JS, Vanderschuren MM, Houwen RHJ, Heijerman HGM, van de Graaf EA, Elias SG, Majoor CJ, Koppelman GH, Roukema J, Bakker M, Janssens HM, van der Meer R, Vries RGJ, Clevers HC, de Jonge HR, Beekman JM, van der Ent CK

Abstract
In vitro drug tests using patient-derived stem cell cultures offer opportunities to individually select efficacious treatments. Here, we provide a study that demonstrates that in vitro drug responses in rectal organoids from individual patients with cystic fibrosis (CF) correlate with changes in two in vivo therapeutic endpoints. We measured individual in vitro efficaciousness using a functional assay in rectum-derived organoids based on forskolin-induced swelling and studied the correlation with in vivo effects. The in vitro organoid responses correlated with both change in pulmonary response and change in sweat chloride concentration. Receiver operating characteristic curves indicated good-to-excellent accuracy of the organoid-based test for defining clinical responses. This study indicates that an in vitro assay using stem cell cultures can prospectively select efficacious treatments for patients and suggests that biobanked stem cell resources can be used to tailor individual treatments in a cost-effective and patient-friendly manner.

PMID: 30759382 [PubMed - in process]

Cardiopulmonary responses to maximal aerobic exercise in patients with cystic fibrosis.

PLoS One. 2019;14(2):e0211219

Authors: Williams CA, Wedgwood KCA, Mohammadi H, Prouse K, Tomlinson OW, Tsaneva-Atanasova K

Abstract
Cystic fibrosis (CF) is a debilitating chronic condition, which requires complex and expensive disease management. Exercise has now been recognised as a critical factor in improving health and quality of life in patients with CF. Hence, cardiopulmonary exercise testing (CPET) is used to determine aerobic fitness of young patients as part of the clinical management of CF. However, at present there is a lack of conclusive evidence for one limiting system of aerobic fitness for CF patients at individual patient level. Here, we perform detailed data analysis that allows us to identify important systems-level factors that affect aerobic fitness. We use patients' data and principal component analysis to confirm the dependence of CPET performance on variables associated with ventilation and metabolic rates of oxygen consumption. We find that the time at which participants cross the gas exchange threshold (GET) is well correlated with their overall performance. Furthermore, we propose a predictive modelling framework that captures the relationship between ventilatory dynamics, lung capacity and function and performance in CPET within a group of children and adolescents with CF. Specifically, we show that using Gaussian processes (GP) we can predict GET at the individual patient level with reasonable accuracy given the small sample size of the available group of patients. We conclude by presenting an example and future perspectives for improving and extending the proposed framework. The modelling and analysis have the potential to pave the way to designing personalised exercise programmes that are tailored to specific individual needs relative to patient's treatment therapies.

PMID: 30759119 [PubMed - in process]

Survival in a bad neighborhood: pancreatic islets in cystic fibrosis.

J Endocrinol. 2019 Feb 01;:

Authors: Norris AW, Ode KL, Merjaneh L, Sanda S, Yi Y, Sun X, Engelhardt JF, Hull RL

Abstract
In cystic fibrosis (CF), ductal plugging and acinar loss result in rapid decline of exocrine pancreatic function. This destructive process results in remodeled islets, with only a modest reduction in insulin producing β cells. However, β-cell function is profoundly impaired, with decreased insulin release and abnormal glucose tolerance being present even in infants with CF. Ultimately, roughly half of CF subjects develop diabetes (termed CF-related diabetes, CFRD). Importantly, CFRD increases CF morbidity and mortality via worsening catabolism and pulmonary disease. Current accepted treatment options for CFRD are aimed at insulin replacement, thereby improving glycemia as well as preventing nutritional losses and lung decline. CFRD is a unique form of diabetes with a distinct pathophysiology that is as yet incompletely understood. Recent studies highlight emerging areas of interest. First, islet inflammation and lymphocyte infiltration are common even in young children with CF and may contribute to β-cell failure. Second, controversy exists in the literature regarding the presence/importance of β-cell intrinsic functions of CFTR and its direct role in modulating insulin release. Third, loss of the CF transmembrane conductance regulator (CFTR) from pancreatic ductal epithelium, the predominant site of its synthesis, results in paracrine effects that impair insulin release. Finally, the degree of β-cell loss in CFRD does not appear sufficient to explain the deficit in insulin release. Thus, it may be possible to enhance the function of the remaining β cells using strategies such as targeting islet inflammation or ductal CFTR deficiency to effectively treat or even prevent CFRD.

PMID: 30759072 [PubMed - as supplied by publisher]

Desmopressin acetate (DDAVP) for preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders.

Cochrane Database Syst Rev. 2019 Feb 13;2:CD009824

Authors: Karanth L, Barua A, Kanagasabai S, Nair NS

Abstract
BACKGROUND: Congenital bleeding disorders can cause obstetric haemorrhage during pregnancy, labour and following delivery. Desmopressin acetate (DDAVP) is found to be an effective drug which can reduce the risk of haemorrhage and can also stop bleeding in certain congenital bleeding disorders. Its use in pregnancy has been controversial. Hence beneficial and adverse effects of DDAVP in these groups of pregnant women should be evaluated.This is an update of a Cochrane Review first published in 2013 and updated in 2015.
OBJECTIVES: To evaluate the efficacy and safety of DDAVP in preventing and treating acute bleeding in pregnant women with bleeding disorders.
SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant and abstract books of conferences proceedings. We also searched several clinical trial registries and grey literature (27 August 2017).Date of most recent search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register: 01 October 2018.
SELECTION CRITERIA: Randomised and quasi-randomised controlled trials investigating the efficacy of DDAVP versus tranexamic acid or factor VIII or rFactor VII or fresh frozen plasma in preventing and treating congenital bleeding disorders during pregnancy were eligible.
DATA COLLECTION AND ANALYSIS: No trials matching the selection criteria were eligible for inclusion.
MAIN RESULTS: No trials matching the selection criteria were eligible for inclusion.
AUTHORS' CONCLUSIONS: No randomised controlled trials were identified investigating the relative effectiveness of DDAVP for bleeding during pregnancy in women with congenital bleeding disorders. In the absence of high-quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials) to decide whether or not to treat women with congenital bleeding disorders with DDAVP.Given the ethical considerations, future randomised controlled trials are unlikely. However, other high-quality controlled studies (such as risk allocation designs, sequential design, parallel cohort design) to investigate the risks and benefits of using DDAVP in this population are needed.Given that there are unlikely to be any trials published in this area, this review will no longer be regularly updated.

PMID: 30758840 [PubMed - as supplied by publisher]

Contribution of the eighth transmembrane segment to the function of the CFTR chloride channel pore.

Cell Mol Life Sci. 2019 Feb 13;:

Authors: Negoda A, Hogan MS, Cowley EA, Linsdell P

Abstract
Our molecular understanding of the cystic fibrosis transmembrane conductance regulator (CFTR)-the chloride channel that is mutated in cystic fibrosis-has been greatly enhanced by a number of recent atomic-level structures of the protein in different conformations. One surprising aspect of these structures was the finding that the eighth of CFTR's 12 membrane-spanning segments (TM8) appeared close to the channel pore. Although functional evidence supports a role for other TMs in forming the pore, such a role for TM8 has not previously been reported. Here, we use patch-clamp recording to investigate the functional role of TM8. Using substituted cysteine accessibility mutagenesis, we find that three amino acid side-chains in TM8 (Y913, Y914, and Y917) are exposed to the extracellular, but not the intracellular, solution. Cysteine cross-linking experiments suggest that Y914 and Y917 are in close proximity to L102 (TM1) and F337 (TM6), respectively, suggesting that TM8 contributes to the narrow selectivity filter region of the pore. Different amino acid substitutions suggest that Y914, and to a lesser extent Y917, play important roles in controlling anion flux through the open channel. Furthermore, substitutions that reduce side-chain volume at Y917 severely affect channel gating, resulting in a channel with an extremely unstable open state. Our results suggest that pore-lining TM8 is among the most important TMs controlling the permeation phenotype of the CFTR channel, and also that movement of TM8 may be critically involved in channel gating.

PMID: 30758641 [PubMed - as supplied by publisher]

Single-breath washout and association with structural lung disease in children with cystic fibrosis.

Pediatr Pulmonol. 2019 Feb 13;:

Authors: Yammine S, Ramsey KA, Skoric B, King L, Latzin P, Rosenow T, Hall GL, Ranganathan SC, AREST CF

Abstract
BACKGROUND: In children with cystic fibrosis (CF) lung clearance index (LCI) from multiple-breath washout (MBW) correlates with structural lung disease. As a shorter test, single-breath washout (SBW) represents an attractive alternative to assess the ventilation distribution, however, data for the correlation with lung imaging are lacking.
METHODS: We assessed correlations between phase III slope (SIII) of double-tracer gas SBW, nitrogen MBW indices (LCI and moment ratios for overall ventilation distribution, Scond, and Sacin for conductive and mainly acinar ventilation, respectively) and structural lung disease assessed by chest computed tomography (CT) in children with CF.
RESULTS: In a prospective cross-sectional study data from MBW, SBW, and chest CT were obtained in 32 children with CF with a median (range) age of 8.2 (5.2-16.3) years. Bronchiectasis was present in 24 (75%) children and air trapping was present in 29 (91%). Median (IQR) SIII of SBW was -138.4 (150.6) mg/mol. We found no association between SIII with either the MBW outcomes or CT scores (n = 23, association with bronchiectasis extent r = 0.10, P = 0.64). LCI and Scond were associated with bronchiectasis extent (n = 23, r = 0.57, P = 0.004; r = 0.60, P = 0.003, respectively).
CONCLUSIONS: Acinar ventilation inhomogeneity measured by SBW was not associated with structural lung disease on CT. Double-tracer SBW added no benefit to indices measured by MBW.

PMID: 30758143 [PubMed - as supplied by publisher]

Tumour necrosis factor signalling in health and disease.

F1000Res. 2019;8:

Authors: Holbrook J, Lara-Reyna S, Jarosz-Griffiths H, McDermott M

Abstract
The master pro-inflammatory cytokine, tumour necrosis factor (TNF), has been shown to modulate multiple signalling pathways, with wide-ranging downstream effects. TNF plays a vital role in the typical immune response through the regulation of a number of pathways encompassing an immediate inflammatory reaction with significant innate immune involvement as well as cellular activation with subsequent proliferation and programmed cell death or necrosis. As might be expected with such a broad spectrum of cellular effects and complex signalling pathways, TNF has also been implicated in a number of disease states, such as rheumatoid arthritis, ankylosing spondylitis, and Crohn's disease. Since the time of its discovery over 40 years ago, TNF ligand and its receptors, TNF receptor (TNFR) 1 and 2, have been categorised into two complementary superfamilies, namely TNF (TNFSF) and TNFR (TNFRSF), and 19 ligands and 29 receptors have been identified to date. There have been significant advances in our understanding of TNF signalling pathways in the last decade, and this short review aims to elucidate some of the most recent advances involving TNF signalling in health and disease.

PMID: 30755793 [PubMed - in process]

Dual β-Lactam Combinations Highly Active against Mycobacterium abscessus Complex In Vitro.

MBio. 2019 Feb 12;10(1):

Authors: Pandey R, Chen L, Manca C, Jenkins S, Glaser L, Vinnard C, Stone G, Lee J, Mathema B, Nuermberger EL, Bonomo RA, Kreiswirth BN

Abstract
As a consequence of a growing population of immunocompromised individuals, including transplant recipients and cystic fibrosis patients, there has been a dramatic increase in chronic infections caused by Mycobacterium abscessus complex (MABC) strains that are usually recalcitrant to effective antibiotic therapy. The recent rise of macrolide resistance in MABC has further complicated this clinical dilemma, dramatizing the need for novel agents. The repurposing of current antibiotics is one rapid path from discovery to patient care. In this study, we have discovered that dual β-lactams, and specifically the combination of ceftazidime with either ceftaroline or imipenem, are synergistic and have clinically relevant activities, with MIC50s of 0.25 (ceftaroline with 100 µg/ml ceftazidime) and 0.5 µg/ml (imipenem with 100 µg/ml ceftazidime) against clinical MABC isolates. Similar synergy was observed in time-kill studies against the M. abscessus ATCC 19977 strain using clinically achievable concentrations of either imipenem (4 µg/ml) or ceftaroline (2 µg/ml), as the addition of ceftazidime at concentrations of ≥50 µg/ml showed a persistent bactericidal effect over 5 days. Treatment of THP-1 human macrophages infected with three different M. abscessus clinical isolates supported the in vitro findings, as the combination of 100 µg/ml ceftazidime and 0.125 µg/ml ceftaroline or 100 µg/ml ceftazidime and 0.25 µg/ml imipenem dramatically reduced the CFU counts to near baseline levels of infection. This study's finding that there is synergy between certain β-lactam combinations against M. abscessus infection provides optimism toward identifying an optimum dual β-lactam treatment regimen.IMPORTANCE The emergence of chronic MABC infections among immunocompromised populations and their inherent and acquired resistance to effective antibiotic therapy have created clinical challenges in advancing patients for transplant surgery and treating those with disease. There is an urgent need for new treatment regimens, and the repurposing of existing antibiotics provides a rapid strategy to advance a laboratory finding to patient care. Our recent discoveries that dual β-lactams, specifically the combination of ceftazidime with ceftaroline or ceftazidime with imipenem, have significant in vitro MIC values and kill curve activities and are effective against infected THP-1 human macrophages provide optimism for a dual β-lactam treatment strategy against MABC infections. The unexpected synergistic activities reported in this study create a new path of discovery to repurpose the large family of β-lactam drugs.

PMID: 30755518 [PubMed - in process]

Synthesis and biological activity of methylated derivatives of the Pseudomonas metabolites HHQ, HQNO and PQS.

Beilstein J Org Chem. 2019;15:187-193

Authors: Thierbach S, Wienhold M, Fetzner S, Hennecke U

Abstract
Selectively methylated analogues of naturally occurring 2-heptyl-4(1H)-quinolones, which are alkaloids common within the Rutaceae family and moreover are associated with quorum sensing and virulence of the human pathogen Pseudomonas aeruginosa, have been prepared. While the synthesis by direct methylation was successful for 3-unsubstituted 2-heptyl-4(1H)-quinolones, methylated derivatives of the Pseudomonas quinolone signal (PQS) were synthesized from 3-iodinated quinolones by methylation and iodine-metal exchange/oxidation. The two N- and O-methylated derivatives of the PQS showed strong quorum sensing activity comparable to that of PQS itself. Staphylococcus aureus, another pathogenic bacterium often co-occurring with P. aeruginosa especially in the lung of cystic fibrosis patients, was inhibited in planktonic growth and cellular respiration by the 4-O-methylated derivatives of HQNO and HHQ, respectively.

PMID: 30745993 [PubMed]