Neutrophil Extracellular Trap (NET)-Mediated Killing of Pseudomonas aeruginosa: Evidence of Acquired Resistance within the CF Airway, Independent of CFTR

The inability of neutrophils to eradicate Pseudomonas aeruginosa within the cystic fibrosis (CF) airway eventually results in chronic infection by the bacteria in nearly 80 percent of patients. Phagocytic killing of P. aeruginosa by CF neutrophils is impaired due to decreased cystic fibrosis transmembrane conductance regulator (CFTR) function and virulence factors acquired by the bacteria. Recently, neutrophil extracellular traps (NETs), extracellular structures composed of neutrophil chromatin complexed with granule contents, were identified as an alternative mechanism of pathogen killing. The hypothesis that NET-mediated killing of P. aeruginosa is impaired in the context of the CF airway was tested. P. aeruginosa induced NET formation by neutrophils from healthy donors in a bacterial density dependent fashion. When maintained in suspension through continuous rotation, P. aeruginosa became physically associated with NETs. Under these conditions, NETs were the predominant mechanism of killing, across a wide range of bacterial densities. Peripheral blood neutrophils isolated from CF patients demonstrated no impairment in NET formation or function against P. aeruginosa. However, isogenic clinical isolates of P. aeruginosa obtained from CF patients early and later in the course of infection demonstrated an acquired capacity to withstand NET-mediated killing in 8 of 9 isolates tested. This resistance correlated with development of the mucoid phenotype, but was not a direct result of the excess alginate production that is characteristic of mucoidy. Together, these results demonstrate that neutrophils can kill P. aeruginosa via NETs, and in vitro this response is most effective under non-stationary conditions with a low ratio of bacteria to neutrophils. NET-mediated killing is independent of CFTR function or bacterial opsonization. Failure of this response in the context of the CF airway may occur, in part, due to an acquired resistance against NET-mediated killing by CF strains of P. aeruginosa

VX-659–Tezacaftor–Ivacaftor in patients with cystic fibrosis and one or two Phe508del alleles

BACKGROUND: The next-generation cystic fibrosis transmembrane conductance regulator (CFTR) corrector VX-659, in triple combination with tezacaftor and ivacaftor (VX-659–tezacaftor–ivacaftor), was developed to restore the function of Phe508del CFTR protein in patients with cystic fibrosis. METHODS: We evaluated the effects of VX-659–tezacaftor–ivacaftor on the processing, trafficking, and function of Phe508del CFTR protein using human bronchial epithelial cells. A range of oral VX-659–tezacaftor–ivacaftor doses in triple combination were then evaluated in randomized, controlled, double-blind, multicenter trials involving patients with cystic fibrosis who were heterozygous for the Phe508del CFTR mutation and a minimal-function CFTR mutation (Phe508del–MF genotypes) or homozygous for the Phe508del CFTR mutation (Phe508del–Phe508del genotype). The primary end points were safety and the absolute change from baseline in the percentage of predicted forced expiratory volume in 1 second (FEV1). RESULTS: VX-659–tezacaftor–ivacaftor significantly improved the processing and trafficking of Phe508del CFTR protein as well as chloride transport in vitro. In patients, VX-659–tezacaftor–ivacaftor had an acceptable safety and side-effect profile. Most adverse events were mild or moderate. VX-659–tezacaftor–ivacaftor resulted in significant mean increases in the percentage of predicted FEV1 through day 29 (P<0.001) of up to 13.3 points in patients with Phe508del–MF genotypes; in patients with the Phe508del–Phe508del genotype already receiving tezacaftor–ivacaftor, adding VX-659 resulted in a further 9.7-point increase in the percentage of predicted FEV1. The sweat chloride concentrations and scores on the respiratory domain of the Cystic Fibrosis Questionnaire–Revised improved in both patient populations. CONCLUSIONS: Robust in vitro activity of VX-659–tezacaftor–ivacaftor targeting Phe508del CFTR protein translated into improvements for patients with Phe508del–MF or Phe508del–Phe508del genotypes. VX-659 triple-combination regimens have the potential to treat the underlying cause of disease in approximately 90% of patients with cystic fibrosis. (Funded by Vertex Pharmaceuticals; VX16-659-101 and VX16-659-001 ClinicalTrials.gov numbers, NCT03224351. opens in new tab and NCT03029455. opens in new tab.

Histo-Blood Group Gene Polymorphisms as Potential Genetic Modifiers of Infection and Cystic Fibrosis Lung Disease Severity

The pulmonary phenotype in cystic fibrosis (CF) is variable; thus, environmental and genetic factors likely contribute to clinical heterogeneity. We hypothesized that genetically determined ABO histo-blood group antigen (ABH) differences in glycosylation may lead to differences in microbial binding by airway mucus, and thus predispose to early lung infection and more severe lung disease in a subset of patients with CF. infection in the severe or mild groups. Multivariate analyses of other clinical phenotypes, including gender, asthma, and meconium ileus demonstrated no differences between groups based on ABH type. infection, nor was there any association with other clinical phenotypes in a group of 808 patients homozygous for the ΔF508 mutation

Prospective multicenter randomized patient recruitment and sample collection to enable future measurements of sputum biomarkers of inflammation in an observational study of cystic fibrosis.

BACKGROUND: Biomarkers of inflammation predictive of cystic fibrosis (CF) disease outcomes would increase the power of clinical trials and contribute to better personalization of clinical assessments. A representative patient cohort would improve searching for believable, generalizable, reproducible and accurate biomarkers. METHODS: We recruited patients from Mountain West CF Consortium (MWCFC) care centers for prospective observational study of sputum biomarkers of inflammation. After informed consent, centers enrolled randomly selected patients with CF who were clinically stable sputum producers, 12 years of age and older, without previous organ transplantation. RESULTS: From December 8, 2014 through January 16, 2016, we enrolled 114 patients (53 male) with CF with continuing data collection. Baseline characteristics included mean age 27 years (SD = 12), 80% predicted forced expiratory volume in 1 s (SD = 23%), 1.0 prior year pulmonary exacerbations (SD = 1.2), home elevation 328 m (SD = 112) above sea level. Compared with other patients in the US CF Foundation Patient Registry (CFFPR) in 2014, MWCFC patients had similar distribution of sex, age, lung function, weight and rates of exacerbations, diabetes, pancreatic insufficiency, CF-related arthropathy and airway infections including methicillin-sensitive or -resistant Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia complex, fungal and non-tuberculous Mycobacteria infections. They received CF-specific treatments at similar frequencies. CONCLUSIONS: Randomly-selected, sputum-producing patients within the MWCFC represent sputum-producing patients in the CFFPR. They have similar characteristics, lung function and frequencies of pulmonary exacerbations, microbial infections and use of CF-specific treatments. These findings will plausibly make future interpretations of quantitative measurements of inflammatory biomarkers generalizable to sputum-producing patients in the CFFPR

Fertility, Pregnancy and Lactation Considerations for Women with CF in the CFTR Modulator Era

Cystic fibrosis (CF) is an autosomal recessive genetic disorder impacting approximately 80,000 people of all races and ethnicities world-wide. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which encodes a protein of the same name. Protein dysfunction results in abnormal chloride and bicarbonate transport in mucus membranes, including those in the respiratory, gastrointestinal and reproductive tracts. Abnormal anion transport causes viscous secretions at the site of involvement. The majority of people with CF succumb to respiratory failure following recurrent cycles of infection and inflammation in the airways. Historically, providers treated the signs and symptoms of CF, but since 2012, have been able to impact the basic defect for the subset of people with CF who have mutations that respond to the new class of drugs, CFTR protein modulators. With the improved health and longevity afforded by CFTR modulators, more women are interested in parenthood and are becoming pregnant. Furthermore, this class of drugs likely increases fertility in women with CF. However, the safety of CFTR modulators in pregnancy and lactation is only beginning to be established. We summarize available data on the impact of CFTR modulators on fertility, pregnancy and lactation in women with CF

Lumacaftor and ivacaftor in the management of patients with cystic fibrosis: current evidence and future prospects

Cystic fibrosis (CF) is a genetic disorder that causes multiorgan morbidity and premature death, most commonly from pulmonary dysfunction. Mutations in the CF transmembrane conductance regulator (CFTR) gene, of which almost 2000 have been described, result in a dysfunctional CFTR protein. This protein is an adenosine triphosphate binding anion channel, present primarily at the surface of epithelial cells. Loss of function mutations in this anion channel result in decreased or absent chloride/bicarbonate transport. The subsequent abnormal salt and water transport at epithelial cell surfaces leads to thickened secretions, and infection or inflammation in affected organs. In the last 20 years, therapeutics have been developed to treat the signs and symptoms of CF. However, in 2012, the small molecule drug, ivacaftor, became the first approved therapy that addresses the basic defect in CF. Ivacaftor is a potentiator of CFTR channels defective in their chloride/bicarbonate gating/conductance, but present at the epithelial cell surface. It is only approved for 10 mutations carried by approximately 7% of the population of patients with CF. F508del is the most common CFTR mutation, present in homozygosity in approximately 50% of patients with CF. The F508del mutation results in multiple CFTR channel defects that require both correction (stabilization of misfolded CFTR and trafficking to the epithelial cell membrane) and potentiation. This article reviews the in vitro and clinical trial data for the potential use of the potentiator, ivacaftor, and the corrector, lumacaftor, in patients with CF

The combination of tezacaftor and ivacaftor in the treatment of patients with cystic fibrosis: clinical evidence and future prospects in cystic fibrosis therapy

Years of tremendous study have dawned a new era for the treatment of cystic fibrosis (CF). For years CF care was rooted in the management of organ dysfunction resulting from the mal-effects of absent anion transport through the CF transmembrane regulator (CFTR) protein. CFTR, an adenosine triphosphate binding anion channel, has multiple functions, but primarily regulates the movement of chloride anions, thiocyanate and bicarbonate across luminal cell membranes. Additional roles include effects on other electrolyte channels such as the epithelial sodium channel (ENaC) and on pulmonary innate immunity. Inappropriate luminal anion movement leads to elevated sweat chloride concentrations, dehydrated airway surface liquid, overall viscous mucous production, and inspissated bile and pancreatic secretions. As a result, patients develop the well-known CF symptoms and disease-defining complications such as chronic cough, oily stools, recurrent pulmonary infections, bronchiectasis, chronic sinusitis and malnutrition. Traditionally, CF has been symptomatically managed, but over the past 6 years those with CF have been offered a new mode of therapy; CFTR protein modulation. These medications affect the basic defect in CF: abnormal CFTR function. Ivacaftor, approved for use in the United States in 2012, is the first medication in CF history to improve CFTR function at the molecular level. Its study and approval were followed by two additional CFTR modulators, lumacaftor/ivacaftor and tezacaftor/ivacaftor. To effectively use currently available CF therapies, clinicians should be familiar with the side effects of the drugs and their impacts on patient outcomes. As many new modulators are on the horizon, this information will equip providers to discuss the benefits and shortcomings of modulator therapy especially in the context of limited healthcare resources

Outcomes of pregnancy in women with cystic fibrosis (CF) taking CFTR modulators - an international survey.

BACKGROUND As their long-term prognosis improves, women with CF are increasingly choosing to have children, but the safety of CFTR modulators in pregnancy and breastfeeding is currently unknown. METHODS A survey was sent to lead clinicians of adult CF centres in Europe, the United Kingdom (UK), United States of America (USA), Australia and Israel requesting anonymised data on pregnancy outcomes in women using CFTR modulators before and during pregnancy and lactation. RESULTS We identified 64 pregnancies in 61 women taking IVA (n = 31), LUM/IVA (n = 26) or TEZ/IVA (n = 7), resulting in 60 live births. In 44 pregnancies, CFTR modulators were either continued throughout pregnancy or temporarily stopped and then restarted. Two maternal complications were deemed related to CFTR modulator therapy; cessation of modulator therapy resulted in clinical decline in 9 women prompting resumption of therapy during pregnancy. No modulator-related complications were reported in infants exposed in utero and/or during breastfeeding. CONCLUSIONS CFTR modulators were reported to be generally well tolerated in pregnancy and breastfeeding, with only 2 maternal complications that were deemed related to CFTR modulator therapy. Women stopping CFTR modulators in pregnancy may experience a decline in clinical status and in the cases identified in this survey, restarting therapy led to a clinical improvement. Current experience remains limited and longer-term prospective follow-up is required to exclude delayed adverse effects

Potential of anti-inflammatory treatment for cystic fibrosis lung disease

Jennifer L Taylor-Cousar1,2, Kelsey A Von Kessel2, Robert Young1, David P Nichols1,21Department of Medicine, National Jewish Health, Denver, Colorado, USA; 2Department of Pediatrics, National Jewish Health, Denver, Colorado, USAAbstract: Cystic fibrosis (CF) is the most common life-shortening genetic disorder in &amp;shy;Caucasians. With improved diagnosis and treatment, survival has steadily increased. &amp;shy;Unfortunately, the overwhelming majority of patients still die from respiratory failure caused by structural damage resulting from airway obstruction, recurrent infection, and inflammation. Here, we discuss the role of inflammation and the development of anti-inflammatory therapies to treat CF lung disease. The inflammatory host response is the least addressed component of CF airway disease at this time. Current challenges in both preclinical and clinical investigation make the identification of suitable anti-inflammatory drugs more difficult. Despite this, many researchers are making significant progress toward this goal and the CF research community has reason to believe that new therapies will emerge from these efforts.Keywords: therapy, cystic fibrosis, survival, inflammatio