DNA mutation motifs in the genes associated with inherited diseases.

PLoS One. 2017;12(8):e0182377

Authors: Růžička M, Kulhánek P, Radová L, Čechová A, Špačková N, Fajkusová L, Réblová K

Abstract
Mutations in human genes can be responsible for inherited genetic disorders and cancer. Mutations can arise due to environmental factors or spontaneously. It has been shown that certain DNA sequences are more prone to mutate. These sites are termed hotspots and exhibit a higher mutation frequency than expected by chance. In contrast, DNA sequences with lower mutation frequencies than expected by chance are termed coldspots. Mutation hotspots are usually derived from a mutation spectrum, which reflects particular population where an effect of a common ancestor plays a role. To detect coldspots/hotspots unaffected by population bias, we analysed the presence of germline mutations obtained from HGMD database in the 5-nucleotide segments repeatedly occurring in genes associated with common inherited disorders, in particular, the PAH, LDLR, CFTR, F8, and F9 genes. Statistically significant sequences (mutational motifs) rarely associated with mutations (coldspots) and frequently associated with mutations (hotspots) exhibited characteristic sequence patterns, e.g. coldspots contained purine tract while hotspots showed alternating purine-pyrimidine bases, often with the presence of CpG dinucleotide. Using molecular dynamics simulations and free energy calculations, we analysed the global bending properties of two selected coldspots and two hotspots with a G/T mismatch. We observed that the coldspots were inherently more flexible than the hotspots. We assume that this property might be critical for effective mismatch repair as DNA with a mutation recognized by MutSα protein is noticeably bent.

PMID: 28767725 [PubMed - indexed for MEDLINE]

Platelet Depletion Impairs Host Defence to Pulmonary Infection with Pseudomonas aeruginosa in Mice.

Am J Respir Cell Mol Biol. 2017 Sep 28;:

Authors: Amison RT, O'Shaughnessy BG, Arnold S, Cleary SJ, Nandi M, Pitchford SC, Bragonzi A, Page CP

Abstract
Platelets have been implicated in pulmonary inflammatory cell recruitment following exposure to allergic and non-allergic stimuli, but little is known about the role of platelets in response to pulmonary infection with Pseudomonas aeruginosa (P. aeruginosa). In this study, we have investigated the impact of the experimental depletion of circulating platelets on a range of inflammatory and bacterial parameters, and their subsequent impact on mortality in a murine model of pulmonary infection with P. aeruginosa. P. aeruginosa infection in mice induced a mild but significant state of peripheral thrombocytopenia in addition to pulmonary platelet accumulation. Increased platelet activation was detected in infected mice through increased levels of the platelet derived mediators PF-4 and β-TG in bronchoalveolar lavage fluid (BALF) and blood plasma. In mice depleted of circulating platelets, pulmonary neutrophil recruitment was significantly reduced 24 hours' post infection, whilst the incidence of systemic dissemination of bacteria was significantly increased compared to non-platelet depleted control mice. Furthermore, mortality rates were increased in bacterial infected mice depleted of circulating platelets. This work demonstrates a role for platelets in the host response towards a gram-negative bacterial respiratory infection.

PMID: 28957635 [PubMed - as supplied by publisher]

Characterization of the Burkholderia cenocepacia TonB Mutant as a Potential Live Attenuated Vaccine.

Vaccines (Basel). 2017 Sep 28;5(4):

Authors: Pradenas GA, Myers JN, Torres AG

Abstract
Burkholderia cenocepacia is an opportunistic pathogen prevalent in cystic fibrosis patients, which is particularly difficult to treat, causing chronic and eventually fatal infections. The lack of effective treatment options makes evident the need to develop alternative therapeutic or prophylactic approaches. Vaccines, and live attenuated vaccines, are an unexplored avenue to treat B. cenocepacia infections. Here we constructed and characterized a B. cenocepacia tonB mutant strain, which was unable to actively transport iron, to test whether this single gene deletion mutant (strain renamed GAP001) protected against an acute respiratory B. cenocepacia lethal infection. Here we show that the mutant strain GAP001 is attenuated, and effective at protecting against B. cenocepacia challenge. Intranasal administration of GAP001 to BALB/c mice resulted in almost complete survival with high degree of bacterial clearance.

PMID: 28956836 [PubMed]

[Iron uptake and biofilm formation in Pseudomonas aeruginosa].

Sheng Wu Gong Cheng Xue Bao. 2017 Sep 25;33(9):1489-1512

Authors: Yu S, Ma L

Abstract
Biofilms are surface-associated communities of microorganisms embedded within self-secreted extracellular polymeric substances, and a major cause of chronic and persistent infections. Respiratory Pseudomona aeruginosa infection is the leading reason for morbidity and mortality in cystic fibrosis patients. The formation of biofilms by P. aeruginosa in the airway is thought to increase persistence and antibiotic resistance during infection. Biofilm formation of P. aeruginosa is regulated by complicated signaling systems including quorum sensing and two-component systems that control the synthesis of extracellular polymeric substances. Furthermore, iron is an essential and scarce nutrient for bacteria and an important signal factor. P. aeruginosa has developed multiple iron uptake systems to sequester enough iron for its survival, with important regulatory roles in both release of virulence factors and formation of biofilms. In this review, we summarize recent advances in biofilm formation and its regulation along with the iron-uptake strategies in P. aeruginosa, to provide new insights and understanding to fight bacterial biofilms.

PMID: 28956396 [PubMed - in process]

Early detection of pulmonary exacerbations in children with Cystic Fibrosis by electronic home monitoring of symptoms and lung function.

Sci Rep. 2017 Sep 27;7(1):12350

Authors: van Horck M, Winkens B, Wesseling G, van Vliet D, van de Kant K, Vaassen S, Groot KW, de Vreede I, Jöbsis Q, Dompeling E

Abstract
Pulmonary exacerbations (PEx) in Cystic Fibrosis (CF) are associated with an increased morbidity and even mortality. We investigated whether early detection of PEx in children with CF is possible by electronic home monitoring of symptoms and lung function. During this one-year prospective multi-centre study, 49 children with CF were asked to use a home monitor three times a week. Measurements consisted of a respiratory symptom questionnaire and assessment of Forced Expiratory Volume in one second (FEV1). Linear mixed-effects and multiple logistic regression analyses were used. In the 2 weeks before a PEx, the Respiratory Symptom Score (RSS) of the home monitor increased (p = 0.051). The FEV1 as percentage of predicted (FEV1%pred) did not deteriorate in the 4 weeks before a PEx. Nevertheless, the FEV1%pred at the start of exacerbation was significantly lower than the FEV1%pred in the non-exacerbation group (mean difference 16.3%, p = 0.012). The combination of FEV1%pred and RSS had a sensitivity to predict an exacerbation of 92.9% (CI 75.0-98.8%) and a specificity of 88.9% (CI 50.7-99.4%). The combination of home monitor FEV1%pred and RSS can be helpful to predict a PEx in children with CF at an early stage.

PMID: 28955051 [PubMed - in process]

MicroRNA-9 downregulates the ANO1 chloride channel and contributes to cystic fibrosis lung pathology.

Nat Commun. 2017 Sep 27;8(1):710

Authors: Sonneville F, Ruffin M, Coraux C, Rousselet N, Le Rouzic P, Blouquit-Laye S, Corvol H, Tabary O

Abstract
Cystic fibrosis results from reduced cystic fibrosis transmembrane conductance regulator protein activity leading to defective epithelial ion transport. Ca(2+)-activated Cl(-) channels mediate physiological functions independently of cystic fibrosis transmembrane conductance regulator. Anoctamin 1 (ANO1/TMEM16A) was identified as the major Ca(2+)-activated Cl(-) channel in airway epithelial cells, and we recently demonstrated that downregulation of the anoctamin 1 channel in cystic fibrosis patients contributes to disease severity via an unknown mechanism. Here we show that microRNA-9 (miR-9) contributes to cystic fibrosis and downregulates anoctamin 1 by directly targeting its 3'UTR. We present a potential therapy based on blockage of miR-9 binding to the 3'UTR by using a microRNA target site blocker to increase anoctamin 1 activity and thus compensate for the cystic fibrosis transmembrane conductance regulator deficiency. The target site blocker is tested in in vitro and in mouse models of cystic fibrosis, and could be considered as an alternative strategy to treat cystic fibrosis.Downregulation of the anoctamin 1 calcium channel in airway epithelial cells contributes to pathology in cystic fibrosis. Here the authors show that microRNA-9 targets anoctamin 1 and that inhibiting this interaction improves mucus dynamics in mouse models.

PMID: 28955034 [PubMed - in process]

Spatial positioning of CFTR's pore-lining residues affirms an asymmetrical contribution of transmembrane segments to the anion permeation pathway.

J Gen Physiol. 2016 May;147(5):407-22

Authors: Gao X, Hwang TC

Abstract
The structural composition of CFTR's anion permeation pathway has been proposed to consist of a short narrow region, flanked by two wide inner and outer vestibules, based on systematic cysteine scanning studies using thiol-reactive probes of various sizes. Although these studies identified several of the transmembrane segments (TMs) as pore lining, the exact spatial relationship between pore-lining elements remains under debate. Here, we introduce cysteine pairs in several key pore-lining positions in TM1, 6, and 12 and use Cd(2+) as a probe to gauge the spatial relationship of these residues within the pore. We find that inhibition of single cysteine CFTR mutants, such as 102C in TM1 or 341C in TM6, by intracellular Cd(2+) is readily reversible upon removal of the metal ion. However, the inhibitory effect of Cd(2+) on the double mutant 102C/341C requires the chelating agent dithiothreitol (DTT) for rapid reversal, indicating that 102C and 341C are close enough to the internal edge of the narrow region to coordinate one Cd(2+) ion between them. We observe similar effects of extracellular Cd(2+) on TM1/TM6 cysteine pairs 106C/337C, 107C/337C, and 107C/338C, corroborating the idea that these paired residues are physically close to each other at the external edge of the narrow region. Although these data paint a picture of relatively symmetrical contributions to CFTR's pore by TM1 and TM6, introducing cysteine pairs between TM6 and TM12 (348C/1141C, 348C/1144C, and 348C/1145C) or between TM1 and TM12 (95C/1141C) yields results that contest the long-held principle of twofold pseudo-symmetry in the assembly of ABC transporters' TMs. Collectively, these findings not only advance our current understanding of the architecture of CFTR's pore, but could serve as a guide for refining computational models of CFTR by imposing physical constraints among pore-lining residues.

PMID: 27114613 [PubMed - indexed for MEDLINE]

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Nationwide trends of hospitalizations for cystic fibrosis in the United States from 2003 to 2013.

Intractable Rare Dis Res. 2017 Aug;6(3):191-198

Authors: Agrawal A, Agarwal A, Mehta D, Sikachi RR, Du D, Wang J

Abstract
Cystic fibrosis (CF) is a multisystem autosomal recessive genetic disorder with significant advances in early diagnosis and treatment in the last decade. It is important to provide updated information regarding these changing demographics as they also reflect a considerable improvement in survival. We analyzed the National Inpatient Sample Database (NIS) in the United States for all patients in which CF was the primary discharge diagnosis (ICD-9: 277.0-277.09) from 2003 to 2013 to evaluate the rate of hospitalizations and determine the cost and mortality associated with CF along with other epidemiological findings. The statistical significance of the difference in the number of hospital discharges, lengths of stays and associated hospital costs over the study period was calculated. In 2003, there were 8,328 hospital discharges with the principal discharge diagnosis of CF in the United States, which increased to 12,590 discharges in 2013 (p < 0.001). The mean hospital charges increased by 57.64% from US$ 60,051 in 2003 to US$ 94,664 in 2013. The aggregate cost of hospital visits increased by 138.31% from US$ 500,105,727 to US$ 1,191,819,760. In the same time, the mortality decreased by 49.3 %. The number of inpatient discharges related to CF has increased from 2003 to 2013. This is due to increased life expectancy of CF patients, resulting in increased disease prevalence. There has been a significant increase in the mean and aggregate cost associated with CF admissions. Over the last decade, many advances have been made in the diagnosis and treatment of CF, consequentially leading to a significant transformation in the epidemiology and demographics of this chronic disease. Rising hospital costs associated with the care of CF patients necessitates future studies analyzing the diagnostic modalities, algorithms and treatment practices of physician's treating CF patients.

PMID: 28944141 [PubMed]

Severe infantile isolated exocrine pancreatic insufficiency caused by the complete functional loss of the SPINK1 gene.

Hum Mutat. 2017 Sep 25;:

Authors: Venet T, Masson E, Talbotec C, Billiemaz K, Touraine R, Gay C, Destombe S, Cooper DN, Patural H, Chen JM, Férec C

Abstract
Exocrine pancreatic insufficiency (EPI) is rare in children, with most if not all cases occurring as part of syndromic conditions such as cystic fibrosis and Shwachman-Diamond syndrome. Here we report two cases, both presenting with severe EPI around five months of age. Characterized by diffuse pancreatic lipomatosis, they otherwise exhibited no remarkable deficiencies in other organs. Novel non-identical homozygous variants (a deletion removing the entire SPINK1 gene and an insertion of a full-length inverted Alu element into the 3'-untranslated region of the SPINK1 gene) resulting in the complete functional loss of the SPINK1 gene (encoding pancreatic secretory trypsin inhibitor) were identified in each patient. Having correlated our findings with current knowledge of SPINK1's role in exocrine pancreas pathophysiology, we propose that complete and partial functional losses of the SPINK1 gene are associated with quite distinct phenotypes, the former causing a new pediatric disease entity of severe infantile isolated EPI. This article is protected by copyright. All rights reserved.

PMID: 28945313 [PubMed - as supplied by publisher]

Bypassing agent prophylaxis in people with hemophilia A or B with inhibitors.

Cochrane Database Syst Rev. 2017 Sep 25;9:CD011441

Authors: Chai-Adisaksopha C, Nevitt SJ, Simpson ML, Janbain M, Konkle BA

Abstract
BACKGROUND: People with hemophilia A or B with inhibitors are at high risk of bleeding complications. Infusion of bypassing agents, such as recombinant activated FVII (rFVIIa) and plasma-derived activated prothrombin complex concentrate, are suggested as alternative therapies to factor VIII (haemophilia A) or IX (haemophilia B) for individuals who no longer respond to these treatments because they develop inhibitory antibodies. The ultimate goal of treatment is to preserve the individual's joints, otherwise destroyed by recurrent bleeds.
OBJECTIVES: To assess the effects of bypassing agent prophylaxis to prevent bleeding in people with hemophilia A or B and inhibitors.
SEARCH METHODS: We searched for relevant studies from the Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched trial registries (16 February 2017) and bibliographic references of retrieved studies were reviewed for potential articles to be included in the review.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register: 12 December 2016.
SELECTION CRITERIA: We included randomized and quasi-randomized controlled studies (cross-over or parallel design) evaluating the effect of prophylaxis treatment with bypassing agents compared with on-demand treatment, or studies evaluating the effects of high-dose compared with low-dose prophylaxis in males of any age with hemophilia with inhibitors.
DATA COLLECTION AND ANALYSIS: Two authors independently selected studies and extracted data and assessed the risk of bias according to standard Cochrane criteria. They assessed the quality of the evidence using the GRADE criteria.
MAIN RESULTS: We included four randomized studies (duration 7 to 15 months) involving 116 males. Risk of bias was judged to be high in two studies due to the open-label study design and in one study due to attrition bias.Two studies compared on-demand treatment to prophylaxis with bypassing agents. In one study (34 males) prophylaxis significantly reduced mean overall bleeding rates, MD - 7.27 (95% CI -9.92 to -4.62) (low quality evidence), mean number of overall bleeding events per month, MD -1.10 (95% CI -1.54 to -0.66), mean number of hemarthrosis, MD -6.60 (95% CI -9.32 to -3.88) (low quality evidence) and mean number of joints that had hemarthrosis, MD -0.90 (95% CI -1.36 to -0.44). The meta-analysis did not conclusively demonstrate significant benefit of prophylaxis on health-related quality of life as measured by Haem-A-QoL score, EQ-5D total score and utility score, EQ-5D VAS and SF-36 physical summary and mental summary score (low quality evidence for all health-related quality of life analyses).The remaining two studies compared dose regimens. The results from one study (22 males) did not conclusively demonstrate benefit or harm of high-dose versus low-dose recombinant activated factor VIIa (rFVIIa) as a prophylaxis for overall bleeding rate, MD -0.82 (95% CI -2.27 to 0.63) (moderate quality evidence), target joint bleeding rate, MD -3.20 (95% CI -7.23 to 0.83) (moderate quality evidence) and serious adverse events, RR 9.00 (95% CI, 0.54 to 149.50) (moderate quality evidence).The overall quality of evidence was moderate to low due to imprecision from limited information provided by studies with small sample sizes and incomplete outcome data in one study.
AUTHORS' CONCLUSIONS: The evidence suggests that prophylaxis with bypassing agents may be effective in reducing bleeding in males with hemophilia with inhibitors. However, there is a lack of evidence for the superiority of one agent over the other or for the optimum dosage regimen. Further studies are needed to evaluate the benefits and harms of prophylaxis treatment on health-related quality of life, as well as the effects of dose of bypassing agents on the outcomes.

PMID: 28944952 [PubMed - as supplied by publisher]

Asymmetry of movements in CFTR's two ATP sites during pore opening serves their distinct functions.

Elife. 2017 Sep 25;6:

Authors: Sorum B, Töröcsik B, Csanády L

Abstract
CFTR, the chloride channel mutated in cystic fibrosis (CF) patients, is opened by ATP binding to two cytosolic nucleotide binding domains (NBDs), but pore-domain mutations may also impair gating. ATP-bound NBDs dimerize occluding two nucleotides at interfacial binding sites; one site hydrolyzes ATP, the other is inactive. The pore opens upon tightening, and closes upon disengagement, of the catalytic site following ATP hydrolysis. Extent, timing, and role of non-catalytic-site movements are unknown. Here we exploit equilibrium gating of a hydrolysis-deficient mutant and apply F value analysis to compare timing of opening-associated movements at multiple locations, from the cytoplasmic ATP sites to the extracellular surface. Marked asynchrony of motion in the two ATP sites reveals their distinct roles in channel gating. The results clarify the molecular mechanisms of functional cross-talk between canonical and degenerate ATP sites in asymmetric ABC proteins, and of the gating defects caused by two common CF mutations.

PMID: 28944753 [PubMed - as supplied by publisher]

Residual Weighted Learning for Estimating Individualized Treatment Rules.

J Am Stat Assoc. 2017;112(517):169-187

Authors: Zhou X, Mayer-Hamblett N, Khan U, Kosorok MR

Abstract
Personalized medicine has received increasing attention among statisticians, computer scientists, and clinical practitioners. A major component of personalized medicine is the estimation of individualized treatment rules (ITRs). Recently, Zhao et al. (2012) proposed outcome weighted learning (OWL) to construct ITRs that directly optimize the clinical outcome. Although OWL opens the door to introducing machine learning techniques to optimal treatment regimes, it still has some problems in performance. (1) The estimated ITR of OWL is affected by a simple shift of the outcome. (2) The rule from OWL tries to keep treatment assignments that subjects actually received. (3) There is no variable selection mechanism with OWL. All of them weaken the finite sample performance of OWL. In this article, we propose a general framework, called Residual Weighted Learning (RWL), to alleviate these problems, and hence to improve finite sample performance. Unlike OWL which weights misclassification errors by clinical outcomes, RWL weights these errors by residuals of the outcome from a regression fit on clinical covariates excluding treatment assignment. We utilize the smoothed ramp loss function in RWL, and provide a difference of convex (d.c.) algorithm to solve the corresponding non-convex optimization problem. By estimating residuals with linear models or generalized linear models, RWL can effectively deal with different types of outcomes, such as continuous, binary and count outcomes. We also propose variable selection methods for linear and nonlinear rules, respectively, to further improve the performance. We show that the resulting estimator of the treatment rule is consistent. We further obtain a rate of convergence for the difference between the expected outcome using the estimated ITR and that of the optimal treatment rule. The performance of the proposed RWL methods is illustrated in simulation studies and in an analysis of cystic fibrosis clinical trial data.

PMID: 28943682 [PubMed - in process]

Animal and model systems for studying cystic fibrosis.

J Cyst Fibros. 2017 Sep 19;:

Authors: Rosen BH, Chanson M, Gawenis LR, Liu J, Sofoluwe A, Zoso A, Engelhardt JF

Abstract
The cystic fibrosis (CF) field is the beneficiary of five species of animal models that lack functional cystic fibrosis transmembrane conductance regulator (CFTR) channel. These models are rapidly informing mechanisms of disease pathogenesis and CFTR function regardless of how faithfully a given organ reproduces the human CF phenotype. New approaches of genetic engineering with RNA-guided nucleases are rapidly expanding both the potential types of models available and the approaches to correct the CFTR defect. The application of new CRISPR/Cas9 genome editing techniques are similarly increasing capabilities for in vitro modeling of CFTR functions in cell lines and primary cells using air-liquid interface cultures and organoids. Gene editing of CFTR mutations in somatic stem cells and induced pluripotent stem cells is also transforming gene therapy approaches for CF. This short review evaluates several areas that are key to building animal and cell systems capable of modeling CF disease and testing potential treatments.

PMID: 28939349 [PubMed - as supplied by publisher]

Pulmonary function and sleep breathing: two new targets for type 2 diabetes care.

Endocr Rev. 2017 Sep 04;:

Authors: Lecube A, Simó R, Pallayova M, Punjabi NM, López-Cano C, Turino C, Hernández C, Barbé F

Abstract
Population based studies showing the negative impact of type 2 diabetes (T2D) on lung function are overviewed. Among the well-recognized pathophysiological mechanisms, the metabolic pathways related to insulin resistance, low-grade chronic inflammation, leptin resistance, microvascular damage, and autonomic neuropathy are emphasized. Histopathological changes are exposed, and findings reported from experimental models are clearly differentiated from those described in humans. The accelerated decline in pulmonary function that appears in patients with cystic fibrosis with related abnormalities of glucose tolerance and diabetes is considered as an example to further investigate the relationship between T2D and the lung. Furthermore, a possible causal link between antihyperglycemic therapies and pulmonary function is examined.T2D similarly affect breathing during sleep, becoming an independent risk factor for higher rates of sleep apnea, leading to nocturnal hypoxemia and daytime sleepiness. Therefore, the impact of T2D on sleep breathing and its influence on sleep architecture is analyzed. Finally, the effect of improving some pathophysiological mechanisms, primarily insulin resistance and inflammation, as well as the optimization of blood glucose control on sleep breathing is evaluated.In summary, the lung should be considered by those providing care for people with diabetes, and raise the central issue of whether the normalization of glucose levels can improve pulmonary function and ameliorate sleep-disordered breathing. Therefore, patients with T2D should be considered a vulnerable group for pulmonary dysfunction. However, further research aimed at elucidating how to screen for the lung impairment in diabetic population in a cost-effective manner is needed.

PMID: 28938479 [PubMed - as supplied by publisher]

Selection of DNA aptamers specific for live Pseudomonas aeruginosa.

PLoS One. 2017;12(9):e0185385

Authors: Soundy J, Day D

Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes significant morbidity and mortality in immunocompromised patients, particular cystic fibrosis sufferers, burns victims, diabetics and neonates. It thrives in moist places where it forms biofilms that are exceedingly difficult to eradicate on hospital surfaces, in water supplies and implanted biomaterials. Using a live cell SELEX approach we selected DNA aptamers to P. aeruginosa grown as biofilms in microfluidic cells. From a pool of aptamer candidates showing tight binding a stem-loop structure was identified as being important for binding. Enhanced binding and increased specificity was achieved by truncating structures and generating chimeric aptamers from the pool of top candidates. The top candidates have low nanomolar binding constants and high discrimination for P. aeruginosa over other Gram-negative bacteria. The aptamers bind both planktonic grown and biofilm grown cells. They do not have intrinsic bacteriostatic or bactericidal activity, but are ideal candidates for modification for use as aptamer-drug conjugates and in biosensors.

PMID: 28937998 [PubMed - in process]

Strategies for the etiological therapy of cystic fibrosis.

Cell Death Differ. 2017 Sep 22;:

Authors: Maiuri L, Raia V, Kroemer G

Abstract
Etiological therapies aim at repairing the underlying cause of cystic fibrosis (CF), which is the functional defect of the cystic fibrosis transmembrane conductance regulator (CFTR) protein owing to mutations in the CFTR gene. Among these, the F508del CFTR mutation accounts for more than two thirds of CF cases worldwide. Two somehow antinomic schools of thought conceive CFTR repair in a different manner. According to one vision, drugs should directly target the mutated CFTR protein to increase its plasma membrane expression (correctors) or improve its ion transport function (potentiators). An alternative strategy consists in modulating the cellular environment and proteostasis networks in which the mutated CFTR protein is synthesized, traffics to its final destination, the plasma membrane, and is turned over. We will analyze distinctive advantages and drawbacks of these strategies in terms of their scientific and clinical dimensions, and we will propose a global strategy for CF research and development based on a reconciliatory approach. Moreover, we will discuss the utility of preclinical biomarkers that may guide the personalized, patient-specific implementation of CF therapies.Cell Death and Differentiation advance online publication, 22 September 2017; doi:10.1038/cdd.2017.126.

PMID: 28937684 [PubMed - as supplied by publisher]

Taurocholate induces biliary differentiation of liver progenitor cells causing hepatic stellate cell chemotaxis in the Ductular Reaction: Role in pediatric cystic fibrosis liver disease.

Am J Pathol. 2017 Sep 18;:

Authors: Pozniak KN, Pearen MA, Pereira TN, Kramer CS, Kalita-De Croft P, Nawaratna SK, Fernandez-Rojo MA, Gobert GN, Tirnitz-Parker JE, Olynyk JK, Shepherd RW, Lewindon PJ, Ramm GA

Abstract
Cystic fibrosis liver disease (CFLD) in children causes progressive fibrosis leading to biliary cirrhosis, however its cause(s) and early pathogenesis are unclear. We hypothesised that a bile acid-induced Ductular Reaction (DR) drives fibrogenesis. We evaluated the DR by cytokeratin-7 immunohistochemistry in liver biopsies, staged for fibrosis, from 60 children with CFLD and demonstrated that the DR was significantly correlated with hepatic fibrosis stage and biliary taurocholate levels. To examine the mechanisms involved in DR induction liver progenitor cells (LPCs) were treated with taurocholate and key events in DR evolution were assessed: LPC proliferation, LPC biliary differentiation and hepatic stellate cell (HSC) chemotaxis. Taurocholate induced a time-dependent increase in LPC proliferation and expression of genes associated with cholangiocyte differentiation (cytokeratin-19, connexin-43, integrin-β4 and γ-glutamyltranspeptidase [GGT]), while the hepatocyte specification marker HNF4α was suppressed. Functional cholangiocyte differentiation was demonstrated via increased acetylated α-tubulin and SOX9 proteins, the number of primary cilia(+) LPCs and increased active GGT enzyme secretion. Taurocholate induced LPCs to release MCP-1, MIP1α and RANTES into conditioned medium causing HSC chemotaxis, which was inhibited by anti-MIP1α. Immunofluorescence confirmed chemokine expression localized to CK7(+) DR and LPCs in CFLD liver biopsies. This study suggests that taurocholate is involved in initiating functional LPC biliary differentiation and the development of the DR, with subsequent induction of chemokines that drive HSC recruitment in CFLD.

PMID: 28935574 [PubMed - as supplied by publisher]

Pediatric lung transplantation.

J Thorac Dis. 2017 Aug;9(8):2675-2683

Authors: Benden C

Abstract
Pediatric lung transplantation has been undertaken since the 1980s, and it is today considered an accepted therapy option in carefully selected children with end-stage pulmonary diseases, providing carefully selected children a net survival benefit and improved health-related quality of life. Nowadays, >100 pediatric lung transplants are done worldwide every year. Here, specific pediatric aspects of lung transplantation are reviewed such as the surgical challenge, effects of immunosuppression on the developing pediatric immune system, and typical infections of childhood, as it is vital to comprehend that children undergoing lung transplants present a real challenge as children are not 'just small adults'. Further, an update on the management of the pediatric lung transplant patient is provided in this review, and future challenges outlined. Indications for lung transplantation in children are different compared to adults, the most common being cystic fibrosis (CF). However, the primary diagnoses leading to pediatric lung transplantation vary considerably by age group. Furthermore, there are regional differences regarding the primary indication for lung transplantation in children. Overall, early referral, careful patient selection and appropriate timing of listing are crucial to achieve real survival benefit. Although allograft function is to be preserved, immunosuppressant-related side effects are common in children post-transplantation. Strategies need to be put into practice to reduce drug-related side effects through careful therapeutic drug monitoring and lowering of target levels of immunosuppression, to avoid acute-reversible and chronic-irreversible renal damage. Instead of a "one fits all approach", tailored immunosuppression and a personalized therapy is to be advocated, particularly in children. Further, infectious complications are a common in children of all ages, accounting for almost 50% of death in the first year post-transplantation. However, chronic lung allograft dysfunction (CLAD) remains the major obstacle for improved long-term survival.

PMID: 28932575 [PubMed]

Comparative Genomics of Burkholderia singularis sp. nov., a Low G+C Content, Free-Living Bacterium That Defies Taxonomic Dissection of the Genus Burkholderia.

Front Microbiol. 2017;8:1679

Authors: Vandamme P, Peeters C, De Smet B, Price EP, Sarovich DS, Henry DA, Hird TJ, Zlosnik JEA, Mayo M, Warner J, Baker A, Currie BJ, Carlier A

Abstract
Four Burkholderia pseudomallei-like isolates of human clinical origin were examined by a polyphasic taxonomic approach that included comparative whole genome analyses. The results demonstrated that these isolates represent a rare and unusual, novel Burkholderia species for which we propose the name B. singularis. The type strain is LMG 28154(T) (=CCUG 65685(T)). Its genome sequence has an average mol% G+C content of 64.34%, which is considerably lower than that of other Burkholderia species. The reduced G+C content of strain LMG 28154(T) was characterized by a genome wide AT bias that was not due to reduced GC-biased gene conversion or reductive genome evolution, but might have been caused by an altered DNA base excision repair pathway. B. singularis can be differentiated from other Burkholderia species by multilocus sequence analysis, MALDI-TOF mass spectrometry and a distinctive biochemical profile that includes the absence of nitrate reduction, a mucoid appearance on Columbia sheep blood agar, and a slowly positive oxidase reaction. Comparisons with publicly available whole genome sequences demonstrated that strain TSV85, an Australian water isolate, also represents the same species and therefore, to date, B. singularis has been recovered from human or environmental samples on three continents.

PMID: 28932212 [PubMed]