First report of whole CFTR gene duplication in a healthy newborn carrying R74W and V855I variants on the same allele.

Cystic fibrosis (CF) is the most common severe autosomal recessive genetic disorder among Caucasians. The improvement of genetic techniques has allowed the identification of an increasing number of genetic variants, including large rearrangements such as duplications. We report the first case of a whole CFTR gene duplication in a healthy newborn, who had normal sweat test, also carrying R74W and V855I variants on the same allele. Familial segregation analysis and the observed frequencies of all the CFTR gene variants, revealed that R74W and V855I were probably both present in a cis arrangement on the allele also containing the duplication (i.e., in a double complex allele). Since R74W is a "variant of varying clinical consequence" its arrangement in trans with one pathogenic variant may not be sufficient to cause a classic CF disease phenotype. Moreover, its duplication could even be an advantage that could compensate for the effect of the alteration.

Treatment of Cystic Fibrosis Patients Homozygous for F508del with Lumacaftor-Ivacaftor (Orkambi®) Restores Defective CFTR Channel Function in Circulating Mononuclear Cells.

The treatment of cystic fibrosis (CF) patients homozygous for the F508del mutation with Orkambi®, a combination of a corrector (lumacaftor) and a potentiator (ivacaftor) of the mutated CFTR protein, resulted in some amelioration of the respiratory function. However, a great variability in the clinical response was also observed. The aim of this study was to evaluate the response to Orkambi® in a small cohort of F508del/F508del patients (n = 14) in terms of clinical and laboratory parameters, including ex vivo CFTR activity in mononuclear cells (MNCs), during a 12-month treatment. Patients responded with an increase in percent predicted forced expiratory volume in 1 s (FEV1%) and body mass index (BMI) as well as with a decrease in white blood cell (WBC) total counts and serum C-reactive protein (CRP) levels, although not significantly. Sweat chloride and CFTR-dependent chloride efflux were found to decrease and increase, respectively, as compared with pre-therapy values. CFTR and BMI showed a statistically significant correlation during Orkambi® treatment. Clustering analysis showed that CFTR, BMI, sweat chloride, FEV1%, and WBC were strongly associated. These data support the notion that CFTR-dependent chloride efflux in MNCs should be investigated as a sensitive outcome measure of Orkambi® treatment in CF patients.

G-CSF and GM-CSF Modify Neutrophil Functions at Concentrations found in Cystic Fibrosis.

The role of colony stimulating factors (CSFs) in cystic fibrosis (CF) circulating neutrophils has not been thoroughly evaluated, considering that the neutrophil burden of lung inflammation in these subjects is very high. The aim of this study was to assess granulocyte-CSF (G-CSF) and granulocyte-macrophage-CSF (GM-CSF) levels in CF patients in various clinical conditions and how these cytokines impact on activation and priming of neutrophils. G-CSF and GM-CSF levels were measured in sputum and serum samples of stable CF patients (n = 21) and in CF patients with acute exacerbation before and after a course of antibiotic therapy (n = 19). CSFs were tested on non CF neutrophils to investigate their effects on reactive oxygen species (ROS) production, degranulation (CD66b, elastase, lactoferrin, MMP-9), and chemotaxis. At very low concentrations found in CF patients (0.005-0.1 ng/ml), both cytokines inhibited ROS production, while higher concentrations (1-5 ng/ml) exerted a stimulatory effect. While either CSF induced elastase and MMP-9 secretion, lactoferrin levels were increased only by G-CSF. Chemotaxis was inhibited by GM-CSF, but was increased by G-CSF. However, when present together at low concentrations, CSFs increased basal and fMLP-stimulated ROS production and chemotaxis. These results suggest the CSF levels that circulating neutrophils face before extravasating into the lungs of CF patients may enhance their function contributing to the airway damage.

CFTR-dependent chloride efflux in cystic fibrosis mononuclear cells is increased by ivacaftor therapy.

AIM: The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) potentiator ivacaftor (Kalydeco®) improves clinical outcome in G551D cystic fibrosis (CF) patients. Here, we have investigated whether ivacaftor has a clinical impact on non-G551D gating mutations and function of circulating leukocytes as well. METHODS: Seven patients were treated with ivacaftor and evaluated at baseline, and at 1-3 and 6 months. Besides clinical and systemic inflammatory parameters, circulating mononuclear cells (MNC) were evaluated for CFTR-dependent chloride efflux by spectrofluorimetry, neutrophils for oxidative burst by cytofluorimetry and HVCN1 mRNA expression by real time PCR. RESULTS: Ivacaftor determined a significant decrease in sweat chloride concentrations at all time points during treatment. Body mass index (BMI), FEV1 , and FVC showed an increasing trend. While C-reactive protein decreased significantly at 2 months, the opposite behavior was noticed for circulating monocytes. CFTR activity in MNC was found to increase significantly at 3 and 6 months. Neutrophil oxidative burst peaked at 2 months and then decreased to baseline. HVCN1 mRNA expression was significantly higher than baseline at 1-3 months and decreased after 6 months of treatment. The chloride efflux in MNC correlated positively with both FEV1 and FVC. On the other hand, sweat chloride correlated positively with CRP and WBC, and negatively with both respiratory function tests. A cluster analysis confirmed that sweat chloride, FEV1 , FVC, BMI, and MNC chloride efflux behaved as a single entity over time. DISCUSSION: In patients with non-G551D mutations, ivacaftor improved both chloride transport in sweat ducts and chloride efflux in MNC, that is, functions directly imputed to CFTR.

The novel complex allele [A238V;F508del] of the CFTR gene: clinical phenotype and possible implications for cystic fibrosis etiological therapies.

Few mutations in cis have been annotated for F508del homozygous patients. Southern Italy patients who at a first analysis appeared homozygous for the F508del mutation (n=63) or compound heterozygous for the F508del and another mutation in the cystic fibrosis transmembrane conductance regulator gene (n=155) were searched for the A238V mutation in exon 6. The allelic frequency of the complex allele [A238V;F508del] was 0.04. When the whole data set was used (comprised also of 56 F508del/F508del and 34 F508del/other mutation controls), no differences reached the statistical significance in the clinical parameters, except chloride concentrations which were lower in [A238V;F508del]/other mutation compared with F508del/other mutation (P=0.03). The two study groups presented less complications than the control groups. Within the minimal data set (34 F508del/F508del, 27 F508del/other mutation, 4 [A238V;F508del]/F508del cases and 5 [A238V;F508del]/other mutation cases); that is, presenting all the variables in each patient, forced expiratory volume in 1 s and forced vital capacity presented a trend to lower levels in the study groups in comparison with the F508del/F508del group, and C-reactive protein approximated statistically significant higher levels in the [A238V;F508del]/other mutation as compared with F508del/F508del patients (P=0.09). The analysis of statistical dependence among the variables showed a significant anticorrelation between chloride and body mass index in the [A238V;F508del]/other mutation group. In conclusion, the complex allele [A238V;F508del] seems to be associated with less general complications than in the control groups, on the other hand possibly giving a worse pulmonary phenotype and higher systemic/local inflammatory response. These findings have implications for the correct recruitment and clinical response of F508del patients in the clinical trials testing the new etiological drugs for cystic fibrosis.

Evaluation of genome-wide expression profiles of blood and sputum neutrophils in cystic fibrosis patients before and after antibiotic therapy.

In seeking more specific biomarkers of the cystic fibrosis (CF) lung inflammatory disease that would be sensitive to antibiotic therapy, we sought to evaluate the gene expression profiles of neutrophils in CF patients before treatment in comparison with non-CF healthy individuals and after antibiotic treatment. Genes involved in neutrophil-mediated inflammation, i.e. chemotaxis, respiratory burst, apoptosis, and granule exocytosis, were the targets of this study. Microarray analysis was carried out in blood and airway neutrophils from CF patients and in control subjects. A fold change (log) threshold of 1.4 and a cut-off of p<0.05 were utilized to identify significant genes. Community networks and principal component analysis were used to distinguish the groups of controls, pre- and post-therapy patients. Control subjects and CF patients before therapy were readily separated, whereas a clear distinction between patients before and after antibiotic therapy was not possible. Blood neutrophils before therapy presented 269 genes down-regulated and 56 up-regulated as compared with control subjects. Comparison between the same patients before and after therapy showed instead 44 genes down-regulated and 72 up-regulated. Three genes appeared to be sensitive to therapy and returned to "healthy" condition: phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), hydrogen voltage-gated channel 1 (HVCN1), and ß-arrestin 1 (ARRB1). The up-regulation of these genes after therapy were confirmed by real time PCR. In airway neutrophils, 1029 genes were differentially expressed post- vs pre-therapy. Of these, 30 genes were up-regulated and 75 down-regulated following antibiotic treatment. However, biological plausibility determined that only down-regulated genes belonged to the gene classes studied for blood neutrophils. Finally, it was observed that commonly expressed genes showed a greater variability in airway neutrophils than that found in blood neutrophils, both before and after therapy. These results indicate more specific targets for future interventions in CF patients involving respiratory burst, apoptosis, and granule exocytosis.

Increase in interleukin-8 production from circulating neutrophils upon antibiotic therapy in cystic fibrosis patients.

BACKGROUND: It is not known whether antibiotic therapy for lung disease in cystic fibrosis (CF) has an influence on circulating polymorphonuclear neutrophil (PMN) function and apoptosis. PATIENTS AND METHODS: Blood PMNs were obtained from 14 CF patients before and after antibiotic treatment for an acute exacerbation, and from 10 healthy controls. PMNs were evaluated for production of reactive oxygen species (ROS) by spectrophotometry, of cytokines in the conditioned medium by ELISA, and apoptotic response by cytofluorimetry. RESULTS: ROS and interleukin (IL)-8 were produced at higher levels by CF PMNs pre-therapy than control PMNs under basal conditions. IL-8 levels further increased after therapy. Early apoptotic response was higher in CF PMNs pre-therapy than in control PMNs, and this pattern did not change after antibiotic treatment. CONCLUSIONS: Circulating PMNs are primed in CF acute patients. Further studies are needed to consider PMN-produced IL-8 as a biomarker to evaluate response to antibiotic therapy in CF patients.

F3/Contactin acts as a modulator of neurogenesis during cerebral cortex development.

The expression of the cell recognition molecule F3/Contactin (CNTN1) is generally associated with the functions of post-mitotic neurons. In the embryonic cortex, however, we find it expressed by proliferating ventricular zone (VZ) precursors. In contrast to previous findings in the developing cerebellum, F3/Contactin transgenic overexpression in the early cortical VZ promotes proliferation and expands the precursor pool at the expense of neurogenesis. At later stages, when F3/Contactin levels subside, however, neurogenesis resumes, suggesting that F3/Contactin expression in the VZ is inversely related to neurogenesis and plays a role in a feedback control mechanism, regulating the orderly progression of cortical development. The modified F3/Contactin profile therefore results in delayed corticogenesis, as judged by downregulation in upper and lower layer marker expression and by BrdU birth dating, indicating that, in this transgenic model, increased F3/Contactin levels counteract neuronal precursor commitment. These effects also occur in primary cultures and are reproduced by addition of an F3/Fc fusion protein to wild type cultures. Together, these data indicate a completely novel function for F3/Contactin. Parallel changes in the generation of the Notch Intracellular Domain and in the expression of the Hes-1 transcription factor indicate that activation of the Notch pathway plays a role in this phenotype, consistent with previous in vitro reports that F3/Contactin is a Notch1 ligand.

A large deletion causes apparent homozygosity for the D1152H mutation in the cystic fibrosis transmembrane regulator (CFTR) gene.

We report the case of a patient with an apparent homozygosity for the D1152H mutation located in exon 18 of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The parents had no personal history of cystic fibrosis (CF) and referred to our laboratory after the diagnosis of fetal bowel hyperechogenicity. The proband presented with meconium ileus and normal sweat chloride test. Sequencing of the CFTR exon 18 together with quantitative genomic assays, such as real-time PCR and the multiplex ligation probe amplification (MLPA) techniques, were performed and revealed that the father was heterozygous for the D1152H mutation and the mother carried a large deletion of the CFTR gene encompassing the genomic sequence including the same mutation. The child inherited D1152H from his father and the large deletion of the CFTR gene from his mother. We suggest that D1152H likely acts as a mild mutation with a dominant effect on the severe deletion of exon 18, considering that after 3 years of clinical examinations the child shows no classical signs and symptoms of CF. Not testing for large deletions in subjects with apparent homozygosity for a mutated CFTR allele could lead to the misidentification of CFTR mutation carrier status.

Genotype-phenotype correlation in cystic fibrosis patients bearing [H939R;H949L] allele.

Cystic fibrosis (CF) is caused by CFTR (cystic fibrosis transmembrane conductance regulator) gene mutations. We ascertained five patients with a novel complex CFTR allele, with two mutations, H939R and H949L, inherited in cis in the same exon of CFTR gene, and one different mutation per patient inherited in trans in a wide population of 289 Caucasian CF subjects from South Italy. The genotype-phenotype relationship in patients bearing this complex allele was investigated. The two associated mutations were related to classical severe CF phenotypes.

Genotype-phenotype correlation in cystic fibrosis patients bearing [H939R; H949L] allele

Cystic fibrosis (CF) is caused by CFTR (cystic fibrosis transmembrane conductance regulator) gene mutations. We ascertained five patients with a novel complex CFTR allele, with two mutations, H939R and H949L, inherited in cis in the same exon of CFTR gene, and one different mutation per patient inherited in trans in a wide population of 289 Caucasian CF subjects from South Italy. The genotype-phenotype relationship in patients bearing this complex allele was investigated. The two associated mutations were related to classical severe CF phenotypes.

Association of interleukin-10 gene haplotypes with Pseudomonas aeruginosa airway colonization in cystic fibrosis.

We genotyped three polymorphisms of the promoter region of the interleukin-10 (IL-10) gene in 220 CF patients from the CF Center of Bari, and tested for an association between genetic variants of the cytokine and chronic airway colonization with Pseudomonas aeruginosa. We found that carriers of the high-IL-10-producing-GCC haplotype had significantly higher risk of chronic pulmonary infection with the pathogen.

Phenotypic expression of genotype-phenotype correlation in cystic fibrosis patients carrying the 852del22 mutation.

Currently, more than 1,000 mutations have been identified in the cystic fibrosis transmembrane regulator (CFTR) gene. While some mutations are common worldwide, the majority are restricted in certain ethnic groups. We have found that in Southern Italy, the 852del22 mutation is well represented with a frequency of 3.5%. We have screened, by reverse dot blot, denaturing gradient gel electrophoresis (DGGE), and gene sequencing, the entire coding regions of CFTR gene in 371 consecutive cystic fibrosis (CF) patients from Southern Italy and have identified 17 patients carrying rare genotypes, among which 13 [6 M; median age 21.7 years (range: 4.5-47.7 years)] carry the 852del22 mutation. To assess the phenotypic expression of CF in patients with the 852del22 mutations we have compared these patients with a group of age and gender matched patients homozygous for the DeltaF508 mutation [n = 34; 19 M; median age 19.9 years (range: 3.8-34.6 years)]. Overall, we found no difference in terms of complications, patient survival (17.6% vs. 30.7%; P = NS), estimated time needed to develop a severe lung disease (22.1 vs. 24.5 years; P = NS), nutritional status, and rate of infection or colonization by most common pathogens between patients in the two groups. Finally, we have found that a late diagnosis was associated with a poor outcome (severe lung disease) regardless of genotype. Our data show that 852del22 mutation results in a phenotypic expression of disease as severe as that determined by the more typical DeltaF508 and, as in the latter case, there is no strict genotype/phenotype correlation.

Transgenic mice expressing F3/contactin from the TAG-1 promoter exhibit developmentally regulated changes in the differentiation of cerebellar neurons.

F3/contactin (CNTN1) and TAG-1 (CNTN2) are closely related axonal glycoproteins that are differentially regulated during development. In the cerebellar cortex TAG-1 is expressed first as granule cell progenitors differentiate in the premigratory zone of the external germinal layer. However, as these cells begin radial migration, TAG-1 is replaced by F3/contactin. To address the significance of this differential regulation, we have generated transgenic mice in which F3/contactin expression is driven by TAG-1 gene regulatory sequences, which results in premature expression of F3/contactin in granule cells. These animals (TAG/F3 mice) display a developmentally regulated cerebellar phenotype in which the size of the cerebellum is markedly reduced during the first two postnatal weeks but subsequently recovers. This is due in part to a reduction in the number of granule cells, most evident in the external germinal layer at postnatal day 3 and in the inner granular layer between postnatal days 8 and 11. The reduction in granule cell number is accompanied by a decrease in precursor granule cell proliferation at postnatal day 3, followed by an increase in the number of cycling cells at postnatal day 8. In the same developmental window the size of the molecular layer is markedly reduced and Purkinje cell dendrites fail to elaborate normally. These data are consistent with a model in which deployment of F3/contactin on granule cells affects proliferation and differentiation of these neurons as well as the differentiation of their synaptic partners, the Purkinje cells. Together, these findings indicate that precise spatio-temporal regulation of TAG-1 and F3/contactin expression is critical for normal cerebellar morphogenesis.