TMEM16F/Anoctamin 6 in Ferroptotic Cell Death.

Cancers (Basel). 2019 May 05;11(5):

Authors: Ousingsawat J, Schreiber R, Kunzelmann K

Abstract
Ca2+ activated Cl- channels (TMEM16A; ANO1) support cell proliferation and cancer growth. Expression of TMEM16A is strongly enhanced in different types of malignomas. In contrast, TMEM16F (ANO6) operates as a Ca2+ activated chloride/nonselective ion channel and scrambles membrane phospholipids to expose phosphatidylserine at the cell surface. Both phospholipid scrambling and cell swelling induced through activation of nonselective ion currents appear to destabilize the plasma membrane thereby causing cell death. There is growing evidence that activation of TMEM16F contributes to various forms of regulated cell death. In the present study, we demonstrate that ferroptotic cell death, occurring during peroxidation of plasma membrane phospholipids activates TMEM16F. Ferroptosis was induced by erastin, an inhibitor of the cystine-glutamate antiporter and RSL3, an inhibitor of glutathione peroxidase 4 (GPX4). Cell death was largely reduced in the intestinal epithelium, and in peritoneal macrophages isolated from mice with tissue-specific knockout of TMEM16F. We show that TMEM16F is activated during erastin and RSL3-induced ferroptosis. In contrast, inhibition of ferroptosis by ferrostatin-1 and by inhibitors of TMEM16F block TMEM16F currents and inhibit cell death. We conclude that activation of TMEM16F is a crucial component during ferroptotic cell death, a finding that may be useful to induce cell death in cancer cells.

PMID: 31060306 [PubMed]

Expert consensus on palivizumab use for respiratory syncytial virus in developed countries.

Paediatr Respir Rev. 2018 Dec 18;:

Authors: Luna MS, Manzoni P, Paes B, Baraldi E, Cossey V, Kugelman A, Chawla R, Dotta A, Fernández RR, Resch B, Carbonell-Estrany X

Abstract
Respiratory syncytial virus (RSV) infection is a leading cause of hospitalisation in early childhood and palivizumab is the only licensed intervention for prevention. Palivizumab guidelines should reflect the latest evidence, in addition to cost-effectiveness and healthcare budgetary considerations. RSV experts from Europe, Canada and Israel undertook a systematic review of the evidence over the last 5 years and developed recommendations regarding prophylaxis in industrialised countries. Almost 400 publications were reviewed. This group recommended palivizumab for: preterm infants (<29 and ≤31 weeks gestational age [wGA] and ≤9 and ≤6 months of age, respectively; high-risk 32-35wGA), former preterm children ≤24 months with chronic lung disease/bronchopulmonary dysplasia, children ≤24 months with significant congenital heart disease; and other high-risk populations, such as children ≤24 months with Down syndrome, pulmonary/neuromuscular disorders, immunocompromised, and cystic fibrosis. Up to 5 monthly doses should be administered over the RSV season. It is our impression that the adoption of these guidelines would help reduce the burden of RSV.

PMID: 31060948 [PubMed - as supplied by publisher]

Who and why; sharing our experiences of developing a standard operating procedure (SOP) to allocate screening slots for highly competitive cystic fibrosis trials.

J Cyst Fibros. 2019 May 03;:

Authors: Dobra R, Scott S, Davies JC, Simmonds NJ

PMID: 31060801 [PubMed - as supplied by publisher]

Use of inhaled imipenem/cilastatin in pediatric patients with cystic fibrosis: A case series.

J Cyst Fibros. 2019 May 03;:

Authors: Jones LA, Doucette L, Dellon EP, Esther CR, McKinzie CJ

Abstract
Mycobacterium abscessus is a rapidly-growing, virulent, non-tuberculous mycobacterium that causes progressive inflammatory lung damage and significant decline in lung functionin patients with cystic fibrosis. M. abscessus complex pulmonary infections are notoriously difficult to treat, and while many antibiotics are approved for children, drug allergies or intolerances can prohibit their use. Intravenous imipenem/cilastatin is among the preferred antibiotics for treatment of M. abscessus, however, its use may result in systemic toxicities including hepatic injury and gastrointestinal effects. Case reports document the successful use of inhaled imipenem/cilastatin in adult cystic fibrosis and non- cystic fibrosis patients with non- M. abscessus pulmonary infections. To our knowledge, similar evidence does not exist for pediatric patients. In this case series, we describe two pediatric patients with cystic fibrosis and previous intolerance or lack of response to standard therapies who received inhaled imipenem/cilastatin for the treatment of chronic M. abscessus infection.

PMID: 31060800 [PubMed - as supplied by publisher]

In vivo proteome of Pseudomonas aeruginosa in airways of cystic fibrosis patients.

J Proteome Res. 2019 May 07;:

Authors: Wu X, Siehnel RJ, Garudathri J, Staudinger BJ, Hisert KB, Ozer EA, Hauser AR, Eng JK, Manoil C, Singh PK, Bruce JE

Abstract
Chronic airway infection with P. aeruginosa (PA) is a hallmark of cystic fibrosis (CF) disease. The mechanisms producing PA persistence in CF therapies remain poorly understood. To gain insight on PA physiology in patient airways and better understand how in vivo bacterial functioning differs from in vitro conditions, we investigated the in vivo proteomes of PA in 35 sputum samples from 11 CF patients. We developed a novel bacterial-enrichment method that relies on differential centrifugation and detergent treatment to enrich for bacteria to improve identification of PA proteome with CF sputum samples. Using two non-redundant peptides as a cutoff, a total of 1304 PA proteins were identified directly from CF sputum samples. The in vivo PA proteomes were compared with the proteomes of ex vivo-grown PA populations from the same patient sample. Label-free quantitation and proteome comparison revealed the in vivo up-regulation of siderophore TonB-dependent receptors, remodeling in central carbon metabolism including glyoxylate cycle and lactate utilization, and alginate overproduction. Knowledge of these in vivo proteome differences or others derived using the presented methodology could lead to future treatment strategies aimed at altering PA physiology in vivo to compromise infectivity or improve antibiotic efficacy.

PMID: 31060355 [PubMed - as supplied by publisher]

Self-powered smart patch for sweat conductivity monitoring.

Microsyst Nanoeng. 2019;5:3

Authors: Ortega L, Llorella A, Esquivel JP, Sabaté N

Abstract
A self-powered skin patch for the measurement of sweat conductivity is presented. The key component of the patch consists of a paper battery that is activated upon absorption of sweat. This body fluid acts as the battery electrolyte, the conductivity of which has a direct impact on the battery-generated output power and voltage. This particular behaviour enables the operation of a very simple and robust conductivity sensor in direct current mode without needing an external power source. The device presented in this paper takes advantage of this new measurement method to develop a sweat patch for screening cystic fibrosis that operates with an extremely simple electronic circuit that minimizes its cost and environmental impact. The patch provides an unambiguous digital result that can be read in an electrochromic display and yields 95% sensitivity and 100% specificity when tested with artificial eccrine perspiration samples.

PMID: 31057930 [PubMed]

Laparoscopic ventral mesh rectopexy for male patient with rectal prolapse- a video vignette.

Colorectal Dis. 2019 May 04;:

Authors: Acar T, Acar N, Güngör F, Sür Y, Haciyanli M

Abstract
Complete rectal prolapse (CRP) is a full-thickness protrusion of the rectum or sigmoid colon through the anal canal [1]. The overall incidence is 0.25%-0.4% and it is 6 times more common in women [2]. Major risk factors include pregnancy, past surgery, pelvic neuropathy or neurological disease, high gastrointestinal parasitic load, chronic obstructive pulmonary disease and cystic fibrosis. Rectal prolapse can be treated with a perineal or abdominal approach [3]. This article is protected by copyright. All rights reserved.

PMID: 31055882 [PubMed - as supplied by publisher]

Health State Utility Data in Cystic Fibrosis: A Systematic Review.

Pharmacoecon Open. 2019 May 03;:

Authors: Mohindru B, Turner D, Sach T, Bilton D, Carr S, Archangelidi O, Bhadhuri A, Whitty JA

Abstract
INTRODUCTION: Cystic fibrosis (CF) is a life-limiting, hereditable condition, with the highest prevalence in Europe. CF treatments have led to improvements in clinical symptoms, disease management and decelerated disease progression. However, little is known about the health state utility (HSU) associated with CF disease states, adverse events, and changes in disease severity. Although HSU data have contributed to existing health economic modelling studies, a lack of such data have been highlighted. This systematic review aims to provide a summary of HSU-related research in CF and highlight related research gaps.
METHODS: Online searches were performed in six databases and studies in any of the following categories were included: (1) estimation of HSUs in CF; (2) mapping studies between patient-reported outcome measures (PROMs) and HSUs; (3) economic evaluations on the management of CF that report primary HSU data; and (4) any CF clinical trial that reported HSU as an outcome.
RESULTS: A total of 17 studies were reviewed, of which 12 provided HSU values for specific CF populations. The remaining five articles provided HSU data that were broken down by CF relevant health states, including lung transplantations, pulmonary exacerbation (PEx) events and forced expiratory volume in 1 s (FEV1).
CONCLUSION: Current HSU data in CF are limited and there is considerable scope for further research, both in providing HSU values for CF and in investigating methods for HSU elicitation/evaluation in CF populations.

PMID: 31054048 [PubMed - as supplied by publisher]

Filamentous bacteriophages affect pathogenicity of Pseudomonas infections in cystic fibrosis.

Nat Rev Microbiol. 2019 May 03;:

Authors: Kelsey R

PMID: 31053807 [PubMed - as supplied by publisher]

A longitudinal characterization of the Non-Cystic Fibrosis Bronchiectasis airway microbiome.

Sci Rep. 2019 May 03;9(1):6871

Authors: Woo TE, Lim R, Heirali AA, Acosta N, Rabin HR, Mody CH, Somayaji R, Surette MG, Sibley CD, Storey DG, Parkins MD

Abstract
A diverse microbiota exists within the airways of individuals with non-cystic fibrosis bronchiectasis (nCFB). How the lung microbiome evolves over time, and whether changes within the microbiome correlate with future disease progression is not yet known. We assessed the microbial community structure of 133 serial sputa and subsequent disease course of 29 nCFB patients collected over a span of 4-16 years using 16S rRNA paired-end sequencing. Interestingly, no significant shifts in the microbial community of individuals were observed during extended follow-up suggesting the microbiome remains relatively stable over prolonged periods. Samples that were Pseudomonas aeruginosa culture positive displayed markedly different microbial community structures compared to those that were positive for Haemophilus influenzae. Importantly, patients with sputum of lower microbial community diversity were more likely to experience subsequent lung function decline as defined by annual change in ≥-1 FEV1% predicted. Shannon diversity values <1 were more prevalent in patients with FEV1 decline (P = 0.002). However, the relative abundance of particular core microbiota constituents did not associate with risk of decline. Here we present data confirming that the microbiome of nCFB individuals is generally stable, and that microbiome-based measurements may have a prognostic role as biomarkers for nCFB.

PMID: 31053725 [PubMed - in process]

An open-label extension study of ivacaftor in children with CF and a CFTR gating mutation initiating treatment at age 2-5 years (KLIMB).

J Cyst Fibros. 2019 Apr 30;:

Authors: Rosenfeld M, Cunningham S, Harris WT, Lapey A, Regelmann WE, Sawicki GS, Southern KW, Chilvers M, Higgins M, Tian S, Cooke J, Davies JC, KLIMB study group

Abstract
BACKGROUND: KIWI (NCT01705145) was a 24-week, single-arm, pharmacokinetics, safety, and efficacy study of ivacaftor in children aged 2 to 5 years with cystic fibrosis (CF) and a CFTR gating mutation. Here, we report the results of KLIMB (NCT01946412), an 84-week, open-label extension of KIWI.
METHODS: Children received age- and weight-based ivacaftor dosages for 84 weeks. The primary outcome was safety. Other outcomes included sweat chloride, growth parameters, and measures of pancreatic function.
RESULTS: All 33 children who completed KIWI enrolled in KLIMB; 28 completed 84 weeks of treatment. Most adverse events were consistent with those reported during KIWI. Ten (30%) children had transaminase elevations >3 × upper limit of normal (ULN), leading to 1 discontinuation in a child with alanine aminotransferase >8 × ULN. Improvements in sweat chloride, weight, and body mass index z scores and fecal elastase-1 observed during KIWI were maintained during KLIMB; there was no further improvement in these parameters.
CONCLUSIONS: Ivacaftor was generally well tolerated for up to 108 weeks in children aged 2 to 5 years with CF and a gating mutation, with safety consistent with the KIWI study. Improvements in sweat chloride and growth parameters during the initial 24 weeks of treatment were maintained for up to an additional 84 weeks of treatment. Prevalence of raised transaminases remained stable and did not increase with duration of exposure during the open-label extension.

PMID: 31053538 [PubMed - as supplied by publisher]

Clinical papers of the year 2018 - Cystic fibrosis.

Paediatr Respir Rev. 2019 Apr 05;:

Authors: Balfour-Lynn IM

Abstract
This paper reviews the most important clinical papers in cystic fibrosis published in 2018, having searched all the literature on Pubmed. Focus is on CFTR modulator therapy, randomised controlled trials, and infection/microbiology issues.

PMID: 31053358 [PubMed - as supplied by publisher]

Aerosolized Bovine Lactoferrin Counteracts Infection, Inflammation and Iron Dysbalance in A Cystic Fibrosis Mouse Model of Pseudomonas aeruginosa Chronic Lung Infection.

Int J Mol Sci. 2019 Apr 30;20(9):

Authors: Cutone A, Lepanto MS, Rosa L, Scotti MJ, Rossi A, Ranucci S, De Fino I, Bragonzi A, Valenti P, Musci G, Berlutti F

Abstract
Cystic fibrosis (CF) is a genetic disorder affecting several organs including airways. Bacterial infection, inflammation and iron dysbalance play a major role in the chronicity and severity of the lung pathology. The aim of this study was to investigate the effect of lactoferrin (Lf), a multifunctional iron-chelating glycoprotein of innate immunity, in a CF murine model of Pseudomonas aeruginosa chronic lung infection. To induce chronic lung infection, C57BL/6 mice, either cystic fibrosis transmembrane conductance regulator (CFTR)-deficient (Cftrtm1UNCTgN(FABPCFTR)#Jaw) or wild-type (WT), were intra-tracheally inoculated with multidrug-resistant MDR-RP73 P. aeruginosa embedded in agar beads. Treatments with aerosolized bovine Lf (bLf) or saline were started five minutes after infection and repeated daily for six days. Our results demonstrated that aerosolized bLf was effective in significantly reducing both pulmonary bacterial load and infiltrated leukocytes in infected CF mice. Furthermore, for the first time, we showed that bLf reduced pulmonary iron overload, in both WT and CF mice. In particular, at molecular level, a significant decrease of both the iron exporter ferroportin and iron storage ferritin, as well as luminal iron content was observed. Overall, bLf acts as a potent multi-targeting agent able to break the vicious cycle induced by P. aeruginosa, inflammation and iron dysbalance, thus mitigating the severity of CF-related pathology and sequelae.

PMID: 31052156 [PubMed - in process]

Natural killer cells kill Burkholderia cepacia complex via a contact-dependent and cytolytic mechanism.

Int Immunol. 2019 May 03;:

Authors: Li SS, Saleh M, Xiang RF, Ogbomo H, Stack D, Huston SH, Mody CH

Abstract
Burkholderia cepacia complex (Bcc), which includes B. cenocepacia and B. multivorans, pose a life-threatening risk to patients with cystic fibrosis. Eradication of Bcc is difficult due to the high level of intrinsic resistance to antibiotics, and failure of many innate immune cells to control the infection. Because of the pathogenesis of Bcc infections, we wondered if a novel mechanism of microbial host defense involving direct antibacterial activity by natural killer (NK) cells might play a role in the control of Bcc. We demonstrate that NK cells bound Burkholderia, resulting in Src family kinase activation as measured by protein tyrosine phosphorylation, granule release of effector proteins such as perforin and contact-dependent killing of the bacteria. These studies provide a means by which NK cells could play a role in host defense against Bcc infection.

PMID: 31051036 [PubMed - as supplied by publisher]

Hsp104 Facilitates the Endoplasmic Reticulum Associated Degradation of Disease-Associated and Aggregation-Prone Substrates.

Protein Sci. 2019 May 03;:

Authors: Doonan LM, Guerriero CJ, Preston GM, Buck TM, Khazanov N, Fisher EA, Senderowitz H, Brodsky JL

Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are selected for ER-associated degradation (ERAD). More than 60 disease-associated proteins are substrates for the ERAD pathway due to the presence of missense or nonsense mutations. In yeast, the Hsp104 molecular chaperone disaggregates detergent-insoluble ERAD substrates, but the spectrum of disease-associated ERAD substrates that may be aggregation-prone is unknown. To determine if Hsp104 recognizes aggregation-prone ERAD substrates associated with human diseases, we developed yeast expression systems for a hydrophobic lipid-binding protein, apolipoprotein B (ApoB), along with a chimeric protein harboring a nucleotide binding domain from the cystic fibrosis transmembrane conductance regulator (CFTR) into which disease-causing mutations were introduced. We discovered that Hsp104 facilitates the degradation of ER-associated ApoB as well as a truncated CFTR chimera in which a premature stop codon corresponds to a disease-causing mutation. Chimeras containing a wild type version of the CFTR domain or a different mutation were stable and thus Hsp104-independent. We also discovered that the detergent solubility of the unstable chimera was lower than the stable chimeras, and Hsp104 helped retrotranslocate the unstable chimera from the ER, consistent with disaggregase activity. To determine why the truncated chimera was unstable, we next performed molecular dynamics simulations and noted significant unraveling of the CFTR nucleotide binding domain. Because human cells lack Hsp104, these data indicate that an alternate disaggregase or mechanism facilitates the removal of aggregation-prone, disease-causing ERAD substrates in their native environments. This article is protected by copyright. All rights reserved.

PMID: 31050848 [PubMed - as supplied by publisher]

Staphylococcus aureus in chronic rhinosinusitis: the effect on the epithelial chloride channel (cystic fibrosis transmembrane conductance regulator, CFTR) and the epithelial sodium channel (ENaC) physiology.

Acta Otolaryngol. 2019 May 03;:1-7

Authors: Saber A, Nakka SS, Hussain R, Hugosson S

Abstract
BACKGROUND: Chronic rhinosinusitis (CRS) is an inflammatory disease of the nose and the paranasal sinuses, often associated with an infection by Staphylococcus aureus (S. aureus). Disturbance in the function of ion channels is regarded as an etiological factor for pathogenesis of CRS.
AIMS: The study aims to measure the mRNA expression of the ENaC and CFTR ion channels in nasal epithelial cells (NECs) and to investigate the effect of both the budesonide and S. aureus on these ion channels.
MATERIALS AND METHOD: NECs biopsies obtained from healthy volunteers and patients with CRS. NECs were infected with S. aureus strains and/or budesonide to study the mRNA expression levels of the ENaC and CFTR ion channels.
RESULTS: The mRNA expression level of CFTR was increased while that of ENaC was decreased. S. aureus infection and budesonide treatment induced a significant modulation of ENaC and CFTR ion channels expression.
CONCLUSION: The CFTR and ENaC ion channel physiology are of importance in the pathogenesis of CRS. Exposure to S. aureus infection and treatment with budesonide modulated the mRNA expression of CFTR and ENaC ion channels.
SIGNIFICANCE: Better understanding of the pathophysiology of CRS.

PMID: 31050570 [PubMed - as supplied by publisher]

Anaerobiosis influences virulence properties of Pseudomonas aeruginosa cystic fibrosis isolates and the interaction with Staphylococcus aureus.

Sci Rep. 2019 May 01;9(1):6748

Authors: Pallett R, Leslie LJ, Lambert PA, Milic I, Devitt A, Marshall LJ

Abstract
The airways of individuals with cystic fibrosis (CF) are abundantly colonised by Staphylococcus aureus and Pseudomonas aeruginosa. Co-infecting hypoxic regions of static mucus within CF airways, together with decreases in pulmonary function, mucus plugging and oxygen consumption by host neutrophils gives rise to regions of anoxia. This study determined the impact of anaerobiosis upon S. aureus-P. aeruginosa interactions in planktonic co-culture and mixed species biofilms in vitro. Whilst anoxia reduced the ability for P. aeruginosa CF isolates to dominate over S. aureus, this occurred in an isolate dependent manner. Investigations into the underlying mechanisms suggest that the anti-staphylococcal compound facilitating P. aeruginosa dominance under normoxia and anoxia is greater than 3 kDa in size and is heat-stable. Not all interspecies interactions studied were antagonistic, as S. aureus exoproducts were shown to restore and enhance P. aeruginosa motility under normoxia and anoxia in an isolate dependent manner. Collectively, this study suggests changes in oxygen availability within regions of the CF lung is likely to influence interspecies interactions and in turn, potentially influence disease progression.

PMID: 31043640 [PubMed - in process]

Applications of lung clearance index in monitoring children with cystic fibrosis.

World J Clin Pediatr. 2019 Apr 09;8(2):15-22

Authors: Fretzayas A, Douros K, Moustaki M, Loukou I

Abstract
A sensitive, reproducible and feasible measure of lung function for monitoring the respiratory health is a prerequisite for the optimization of management of the patients with cystic fibrosis (CF). Spirometry has been considered the method of choice, although it is applicable only in children older than 6 years of age, as good cooperation is necessary for its proper performance. However, over the last 15 years, scientific interest in gas dilution techniques and particularly in multiple breath wash out (MBW) method has been revived. The most commonly reported index of MBW is lung clearance index (LCI). The aim of this review is to present the most recent developments in the application of LCI as a monitoring index of respiratory status of CF patients. LCI is a sensitive and reproducible marker of ventilation inhomogeneity. It is more sensitive than spirometry and, unlike spirometry; it can be performed across the whole pediatric age range. Since it is dependent on body size, until at least the age of 6 years, the relative and not the absolute changes are more appropriate for providing clinically meaningful conclusion on ventilation inhomogeneity. Until now, MBW has been mainly used as a research tool. Based on the currently available data LCI cannot safely predict high-resolution computed tomography findings in children with CF, especially in infants. It can be used as an end-point measure for the assessment of beneficial effect of interventions. However, its utility as an outcome measure for the efficacy of therapeutic interventions seems to be dependent on the pathophysiologic mechanisms that underlie each intervention. It seems that more studies, especially longitudinal ones, are required in order to fully clarify the clinical usefulness of LCI, not only in the research setting, but also in every day practice of CF clinic.

PMID: 31041164 [PubMed]

Blocking RpoN reduces virulence of Pseudomonas aeruginosa isolated from cystic fibrosis patients and increases antibiotic sensitivity in a laboratory strain.

Sci Rep. 2019 Apr 30;9(1):6677

Authors: Lloyd MG, Vossler JL, Nomura CT, Moffat JF

Abstract
Multidrug-resistant organisms are increasing in healthcare settings, and there are few antimicrobials available to treat infections from these bacteria. Pseudomonas aeruginosa is an opportunistic pathogen in burn patients and individuals with cystic fibrosis (CF), and a leading cause of nosocomial infections. P. aeruginosa is inherently resistant to many antibiotics and can develop resistance to others, limiting treatment options. P. aeruginosa has multiple sigma factors to regulate transcription. The alternative sigma factor, RpoN (σ54), regulates many virulence genes and is linked to antibiotic resistance. Recently, we described a cis-acting peptide, RpoN*, which is a "molecular roadblock", binding consensus promoters at the -24 site, blocking transcription. RpoN* reduces virulence of P. aeruginosa laboratory strains, but its effects in clinical isolates was unknown. We investigated the effects of RpoN* on phenotypically varied P. aeruginosa strains isolated from CF patients. RpoN* expression reduced motility, biofilm formation, and pathogenesis in a P. aeruginosa-C. elegans infection model. Furthermore, we investigated RpoN* effects on antibiotic susceptibility in a laboratory strain. RpoN* expression increased susceptibility to several beta-lactam-based antibiotics in strain P. aeruginosa PA19660 Xen5. We show that using a cis-acting peptide to block RpoN consensus promoters has potential clinical implications in reducing virulence and improving antibiotic susceptibility.

PMID: 31040330 [PubMed - in process]

Structural analogues of roscovitine rescue the intracellular traffic and the function of ER-retained ABCB4 variants in cell models.

Sci Rep. 2019 Apr 30;9(1):6653

Authors: Vauthier V, Ben Saad A, Elie J, Oumata N, Durand-Schneider AM, Bruneau A, Delaunay JL, Housset C, Aït-Slimane T, Meijer L, Falguières T

Abstract
Adenosine triphosphate binding cassette transporter, subfamily B member 4 (ABCB4) is the transporter of phosphatidylcholine at the canalicular membrane of hepatocytes. ABCB4 deficiency, due to genetic variations, is responsible for progressive familial intrahepatic cholestasis type 3 (PFIC3) and other rare biliary diseases. Roscovitine is a molecule in clinical trial that was shown to correct the F508del variant of cystic fibrosis transmembrane conductance regulator (CFTR), another ABC transporter. In the present study, we hypothesized that roscovitine could act as a corrector of ABCB4 traffic-defective variants. Using HEK and HepG2 cells, we showed that roscovitine corrected the traffic and localisation at the plasma membrane of ABCB4-I541F, a prototypical intracellularly retained variant. However, roscovitine caused cytotoxicity, which urged us to synthesize non-toxic structural analogues. Roscovitine analogues were able to correct the intracellular traffic of ABCB4-I541F in HepG2 cells. Importantly, the phospholipid secretion activity of this variant was substantially rescued by three analogues (MRT2-235, MRT2-237 and MRT2-243) in HEK cells. We showed that these analogues also triggered the rescue of intracellular traffic and function of two other intracellularly retained ABCB4 variants, i.e. I490T and L556R. Our results indicate that structural analogues of roscovitine can rescue genetic variations altering the intracellular traffic of ABCB4 and should be considered as therapeutic means for severe biliary diseases caused by this class of variations.

PMID: 31040306 [PubMed - in process]