ABSTRACT: Cystic fibrosis (CF)-related diabetes (CFRD) is an increasingly common and devastating comorbidity of CF, affecting ~35% of adults with CF. However, the underlying causes of CFRD are unclear. Here, we examined cystic fibrosis transmembrane conductance regulator (CFTR) islet expression and whether the CFTR participates in islet endocrine cell function using murine models of b cell CFTR deletion, and normal and CF human pancreas and islets. Specific deletion of CFTR from murine b cells did not affect b cell function. In human islets, CFTR mRNA was minimally expressed, and CFTR protein/electrical activity was not detected. Isolated CF/CFRD islets demonstrated appropriate insulin and glucagon secretion with few changes in key islet-regulatory transcripts. Furthermore, ~65% of b cell area was lost in CF donors, compounded by pancreatic remodeling and immune infiltration of the islet. These results indicate that CFRD is not caused by intrinsic islet dysfunction from CFTR mutation, but rather, by b cell loss and intra-islet inflammation in the setting of a complex pleiotropic disease
Project description:Dysfunction of the cystic fibrosis transmembrane regulator (CFTR) in cystic fibrosis (CF) results in exaggerated and chronic inflammation as well as increased susceptibility to chronic pulmonary infections, in particular with Pseudomonas aeruginosa. Based on the concept that host immune responses do not seem to be adequate to eradicate P.aeruginosa from the lungs of CF patients and that dendritic cells (DC) play an important role in initiating and shaping adaptive immune responses, this study analyzed the role of CFTR in bone marrow-derived murine DC from CFTR knockout (CF) mice with and without exposure to P.aeruginosa. DC expressed CFTR mRNA and protein, although at much lower levels compared to whole lung. Microarray analysis of gene expression levels in DC generated from CF and wild type (WT) mice revealed significantly different expression of 16 genes in CF DC compared to WT DC. Among the genes with lower expression in CF DC was Caveolin-1, a membrane lipid raft protein. Messenger RNA and protein levels of Caveolin-1 were decreased in the CF DC compared to WT DC. Consistently, the active form of sterol-responsive element binding protein (SREBP), a negative regulator of Caveolin-1 expression, was increased in CF DC. Following exposure to P.aeruginosa, gene expression levels in CF and WT DC changed for 912 genes involved in inflammation, chemotaxis, signaling, cell cycling and apoptosis more than 1.5-fold. Among the genes that showed a different response between WT and CF DC infected with P.aeruginosa, were 3Î²-hydroxysterol-Î7 reductase (Dhcr7) and stearoyl-CoA desaturase 2 (Scd2), two enzymes involved in the lipid metabolism that are also regulated by SREBP. These results suggest that CFTR dysfunction in non-epithelial cells results in changes in the expression of genes encoding factors involved in membrane structure and lipid-metabolism. These membrane alterations in immune cells may contribute to the abnormal inflammatory and immune response characteristic of CF. Experiment Overall Design: comparison of gene expression in dendritic cells of cystic fibrosis mice without or with Pseudosmonas aeruginosa infection vs wild type dendritic cell controls
Project description:Cystic Fibrosis (CF) is a recessively inherited disease caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. CFTR has a pivotal role in the onset of CF, and several proteins are directly or indirectly involved in its homeostasis. To study these CFTR interactors at protein species level, we used a functional proteomics approach combining 2D-DIGE, mass spectrometry and enrichment analysis. A human cystic fibrosis bronchial epithelial cell line (CFBE41o-) was used for analysis. 74 differentially expressed spots were identified and some were validated by western-blot. Enrichment analysis highlighted molecular pathways in which ezrin, HSP70, endoplasmin and lamin A/C, in addition to CFTR, were considered central hubs in CFTR homeostasis. These proteins acquire different functions through post-translational modifications, emphasizing the importance of studying the CF proteome at protein species level. Moreover, serpin H1, prelamin A/C, protein-SET and cystatin-B were associated for the first time to CF, demonstrating the importance of heat shock response, cross-talk between the cytoskeleton and signal transduction, chronic inflammation and alteration of CFTR gating in the pathophysiology of the disease. These results open new perspectives for the understanding of the proteostasis network, characteristic of CF pathology, and could provide a springboard for new therapeutic strategies.
Project description:Our laboratory has held a long interest in the glycosylation changes seen on the surface of airway epithelia of patients with the disease cystic fibrosis (CF). Experiments from our laboratory have detailed a CF glycosylation phenotype of increased Fuca1,3/4 and decreased Fuca1,2 and sialic acid on the surfaces of immortalized and primary CF cells compared to non-CF cells. Further, we have shown that gene transfer and subsequent expression of a wild type CF plasmid in CF airway cells results in correction or reversal of this glycosylation phenotype. We hypothesize that the changes in glycosylation seen in CF cells are key in the pathophysiology of the cystic fibrosis airway disease. For example, it has been shown that Pseudomonas aeruginosa, a bacterium that has a predilection for colonizing CF airways, adheres to asialylated glycolipids and glycoconjugates with terminal Fuca1,3/4. One focus of our laboratory is to elucidate the etiology of the glycosylation changes seen in CF cells and the mechanism by which these changes are reversed by wild type CFTR gene transfer. We propose to study the gene expression of immortalized and primary CF and non-CF airway epithelial cells: 1. CF/T43 vs. BEAS-2B cells. These are two widely used immortalized airway cell lines that we have used extensively in the past. 2. C38 cells; C38 cells are IB3 cells expressing wtCFTR. The experimental focus is to elucidate the etiology of the glycosylation changes seen in Cystic Fibrosis (CF) cells and the mechanism by which these changes are reversed by wild type CFTR gene transfer. To do so, the gene expression of immortalized and primary CF and non-CF airway epithelial cells were compared and studied. Cell lines used were CF/T43 and BEAS-2B, both widely used immortalized airway cell lines. Other cell lines studied included C38 cell lines (clonal derivatives of IB3 cells expressing wtCFTR).
Project description:Gene expression profiles were recorded from rectal suction specimens of Cystic Fibrosis (CF) patients, carrying the CF-specific D508 mutated CFTR-allele. These profiles were compared with gene expression profiles from rectal suction specimens of non-CF subjects (control).
Project description:We have compared gene expression in human nasal brushing cells from 19 cystic fibrosis (CF) patients and 19 healthy controls using a 5.2K cDNA microarray. Our aim is to identify new disease biomarkers for the Cystic Fibrosis Gene Therapy Consortium. These markers will be used to report more effectively on the response to the administration of gene therapy in vivo. Cystic Fibrosis is a recessive genetic disease caused by mutations in the cystic fibrosis conductance regulator (CFTR) gene which encodes a chloride ion channel. The most common mutation is the ∆F508 mutation, present on 70% of CF chromosomes in Caucasian populations. The disease affects many organs in the body such as the pancreas, liver, sweat glands, small intestine and reproductive tracts but is most commonly associated with progressive, inflammatory lung disease. The current average life expectancy of CF patients is 35 years. Gene therapy is being developed as a treatment for CF airway disease, however, means of measuring the efficiency and efficacy of gene therapy in vivo are lacking. This is mainly due to the difficulty in measuring the chloride conductance of CFTR in cells and tissues. Furthermore, clinical assays for measuring improvements in lung function are insensitive. Surrogate markers of inflammation and CFTR function will therefore be important for the effective assessment of gene therapy in vivo. We have analysed gene expression in human nasal epithelium as this is considered an accessible surrogate for the conducting airways where disease manifests in the majority of patients. Additionally, this tissue will be sampled in clinical trials.
Project description:Whole transcriptional analysis of normal 16HBE14o- cells, cystic fibrosis (CF) patients-derived CFBE41o- cells, and WT-CFTR-rescued CFBE41o- cells. We utilized the gene expression data to understand the transcriptional regulation underlying the loss of CFTR function.
Project description:Cystic fibrosis (CF) is a life-shortening disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Although bacterial lung infection and the resulting inflammation cause most of the morbidity and mortality, how loss of CFTR first disrupts airway host defense has remained uncertain. We asked what abnormality impairs elimination when a bacterium lands on the pristine surface of a newborn CF airway? To investigate this defect, we interrogated the viability of individual bacteria immobilized on solid grids and placed on the airway surface. As a model we studied CF pigs, which spontaneously develop hallmark features of CF lung disease. At birth, their lungs lack infection and inflammation, but have a reduced ability to eradicate bacteria. Here we show that in newborn wild-type pigs, the thin layer of airway surface liquid (ASL) rapidly killed bacteria in vivo, when removed from the lung, and in primary epithelial cultures. Lack of CFTR reduced bacterial killing. We found that ASL pH was more acidic in CF, and reducing pH inhibited the antimicrobial activity of ASL. Reducing ASL pH diminished bacterial killing in wild-type pigs, and increasing ASL pH rescued killing in CF pigs. These results directly link the initial host defense defect to loss of CFTR, an anion channel that facilitates HCO3- transport. Without CFTR, airway epithelial HCO3- secretion is defective, ASL pH falls and inhibits antimicrobial function, and thereby impairs killing of bacteria that enter the newborn lung. These findings suggest that increasing ASL pH might prevent the initial infection in patients with CF and that assaying ASL pH or bacterial killing could report on the benefit of therapeutic interventions. 11 samples of trachea primary airway epithelial cultures representing CFTR+/+ and CFTR-/- pigs. Pig samples representing 14 bronchus and 12 trachea tissue samples submitted in GSE21071.
Project description:In cystic fibrosis (CF), loss of CF transmembrane conductance regulator (CFTR)-dependent bicarbonate secretion precipitates the accumulation of viscous mucus in the lumen of respiratory and gastrointestinal epithelial tissues. We investigated whether the combination of elexacaftor (ELX), ivacaftor (IVA) and tezacaftor (TEZ), apart from its well-documented effect on Phe508del-CFTR-mediated chloride transport, also restores bicarbonate transport.
Project description:The F508del mutation, the most frequent in cystic fibrosis (CF), impairs the maturation of the CFTR chloride channel. The F508del defect can be partially overcome at low temperature (27 Â°C) or with pharmacological correctors. The rescue elicited by low temperature may involve a direct stabilization of mutant CFTR protein and/or a change in cell transcriptome that creates a more favorable proteostasis environment. To assess the effect of low temperature on gene expression we investigated the transcriptome of bronchial epithelial cells derived from CF with F508del mutation. Cells were kept under control conditions or incubated at 27 Â°C. Microarray data indicate that hypothermia induces a profound and global change in gene expression that may be in part responsible for rescue of F508del-CFTR. Bronchial epithelial cells from cystic fibrosis patients homozygotes for F508del mutation were isolated. Cells differentiated as epithelial monolayers on porous membranes (Snapwell inserts) were incubated for 24 hours at 27 Â°C or kept under control conditions. Rescue of mutant CFTR channel by low temperature was checked by measuring transepithelial chloride currents with the Ussing chamber technique. Total RNA was extracted from treated and control cells to assess changes in gene expression with microarrays.
Project description:A deficiency in cystic fibrosis transmembrane conductance regulator (CFTR) function in cystic fibrosis (CF) leads to chronic lung disease. However, the molecular mechanisms are not well understood and therapies that can help all patients remain elusive. CF is associated with abnormalities in fatty acids, ceramides and cholesterol, therefore we examined the impact of CFTR deficiency on lipid metabolism and pro-inflammatory signaling in airway epithelium using mass spectrometric, protein array and RNAseq analyses. We observed a striking imbalance in fatty acid and ceramide metabolism, associated with chronic oxidative stress under basal conditions in CF mouse lung and well differentiated bronchial epithelial cell cultures of CFTR knock out pig and CF patients. Cell autonomous features of all three CF models included high ratios of ω-6- to ω-3-polyunsaturated fatty acids and long- to very long- chain ceramide species (LCC/VLCC). The anti-oxidants glutathione (GSH) and deferoxamine partially corrected the lipid profile indicating that oxidative stress may promote the lipid abnormalities. CFTR-targeted modulators reduced the lipid imbalance and apparent oxidative stress, confirming the CFTR dependence of lipid ratios. RNA sequencing and protein array analysis revealed higher expression and shedding of cytokines and growth factors from CF epithelial cells compared to non-CF cells, consistent with sterile inflammation and tissue remodeling under basal conditions. Treatment with antioxidants or CFTR modulators that mimic the approved combination therapies, Orkambi and Trikafta, did not suppress the inflammatory phenotype. These results suggest that anti-inflammatory therapies may provide additional benefit for CF patients taking CFTR modulator drugs.