A Genotypic-Oriented View of CFTR Genetics Highlights Specific Mutational Patterns Underlying Clinical Macrocategories of Cystic Fibrosis.

Cystic fibrosis (CF) is a monogenic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The genotype-phenotype relationship in this disease is still unclear, and diagnostic, prognostic and therapeutic challenges persist. We enrolled 610 patients with different forms of CF and studied them from a clinical, biochemical, microbiological and genetic point of view. Overall, there were 125 different mutated alleles (11 with novel mutations and 10 with complex mutations) and 225 genotypes. A strong correlation between mutational patterns at the genotypic level and phenotypic macrocategories emerged. This specificity appears to largely depend on rare and individual mutations, as well as on the varying prevalence of common alleles in different clinical macrocategories. However, 19 genotypes appeared to underlie different clinical forms of the disease. The dissection of the pathway from the CFTR mutated genotype to the clinical phenotype allowed to identify at least two components of the variability usually found in the genotype-phenotype relationship. One component seems to depend on the genetic variation of CFTR, the other component on the cumulative effect of variations in other genes and cellular pathways independent from CFTR. The experimental dissection of the overall biological CFTR pathway appears to be a powerful approach for a better comprehension of the genotype-phenotype relationship. However, a change from an allele-oriented to a genotypic-oriented view of CFTR genetics is mandatory, as well as a better assessment of sources of variability within the CFTR pathway.

Cystic fibrosis transmembrane conductance regulator (CFTR) allelic variants relate to shifts in faecal microbiota of cystic fibrosis patients.

INTRODUCTION: In this study we investigated the effects of the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene variants on the composition of faecal microbiota, in patients affected by Cystic Fibrosis (CF). CFTR mutations (F508del is the most common) lead to a decreased secretion of chloride/water, and to mucus sticky secretions, in pancreas, respiratory and gastrointestinal tracts. Intestinal manifestations are underestimated in CF, leading to ileum meconium at birth, or small bowel bacterial overgrowth in adult age. METHODS: Thirty-six CF patients, fasting and under no-antibiotic treatment, were CFTR genotyped on both alleles. Faecal samples were subjected to molecular microbial profiling through Temporal Temperature Gradient Electrophoresis and species-specific PCR. Ecological parameters and multivariate algorithms were employed to find out if CFTR variants could be related to the microbiota structure. RESULTS: Patients were classified by two different criteria: 1) presence/absence of F508del mutation; 2) disease severity in heterozygous and homozygous F508del patients. We found that homozygous-F508del and severe CF patients exhibited an enhanced dysbiotic faecal microbiota composition, even within the CF cohort itself, with higher biodiversity and evenness. We also found, by species-specific PCR, that potentially harmful species (Escherichia coli and Eubacterium biforme) were abundant in homozygous-F508del and severe CF patients, while beneficial species (Faecalibacterium prausnitzii, Bifidobacterium spp., and Eubacterium limosum) were reduced. CONCLUSIONS: This is the first report that establishes a link among CFTR variants and shifts in faecal microbiota, opening the way to studies that perceive CF as a 'systemic disease', linking the lung and the gut in a joined axis.

Treatment of low bone density in young people with cystic fibrosis: a multicentre, prospective, open-label observational study of calcium and calcifediol followed by a randomised placebo-controlled trial of alendronate.

BACKGROUND: Long-term complications of cystic fibrosis include osteoporosis and fragility fractures, but few data are available about effective treatment strategies, especially in young patients. We investigated treatment of low bone mineral density in children, adolescents, and young adults with cystic fibrosis. METHODS: We did a multicentre trial in two phases. We enrolled patients aged 5-30 years with cystic fibrosis and low bone mineral density, from ten cystic fibrosis regional centres in Italy. The first phase was an open-label, 12-month observational study of the effect of adequate calcium intake plus calcifediol. The second phase was a 12-month, double-blind, randomised, placebo-controlled, parallel group study of the efficacy and safety of oral alendronate in patients whose bone mineral apparent density had not increased by 5% or more by the end of the observational phase. Patients were randomly assigned to either alendronate or placebo. Both patients and investigators were masked to treatment assignment. We used dual x-ray absorptiometry at baseline and every 6 months thereafter, corrected for body size, to assess lumbar spine bone mineral apparent density. We assessed bone turnover markers and other laboratory parameters every 3-6 months. The primary endpoint was mean increase of lumbar spine bone mineral apparent density, assessed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT01812551. FINDINGS: We screened 540 patients and enrolled 171 (mean age 13·8 years, SD 5·9, range 5-30). In the observational phase, treatment with calcium and calcifediol increased bone mineral apparent density by 5% or more in 43 patients (25%). 128 patients entered the randomised phase. Bone mineral apparent density increased by 16·3% in the alendronate group (n=65) versus 3·1% in the placebo group (n=63; p=0·0010). 19 of 57 young people (33·3%) receiving alendronate attained a normal-for-age bone mineral apparent density Z score. In the observational phase, five patients had moderate episodes of hypercalciuria, which resolved after short interruption of calcifediol treatment. During the randomised phase, one patient taking alendronate had mild fever versus none in the placebo group; treatment groups did not differ significantly for other adverse events. INTERPRETATION: Correct calcium intake plus calcifediol can improve bone mineral density in some young patients with cystic fibrosis. In those who do not respond to calcium and calcifediol alone, alendronate can safely and effectively increase bone mineral density. FUNDING: Telethon Foundation (Italy).

Slow-release insulin in cystic fibrosis patients with glucose intolerance: a randomized clinical trial.

BACKGROUND: Early stages of glucose metabolism impairment are a period at risk in the long-term prognosis of cystic fibrosis (CF). Slow-release synthetic insulin glargine can be a therapeutic tool in this metabolic condition. METHODS: In this phase 3 multicenter, controlled, two-arm, randomized clinical study, glargine was administered up to a dosage of 0.15 U/kg/die for a period of 18 months. Primary endpoint was the improvement of nutritional status [body mass index (BMI) Z score], while glucose tolerance [hemoglobin A1c (HbA1C) and respiratory function (FEV1 predicted] improvement were the secondary endpoints. RESULTS: Thirty-four subjects (18 in the glargine arm and 16 in the control arm) were evaluated. Adherence to insulin treatment was excellent. No significant adverse events were reported. There were no significant differences in BMI, HbA1C and FEV1 values between the two groups nor within groups, except for HbA1C improvement in the glargine arm at month +18 (p = 0.04). CONCLUSIONS: Glargine treatment was well accepted and tolerated. No real efficacy in improving clinical and glycometabolic conditions was demonstrated. Further studies are necessary to test glargine at higher dosage and for a longer follow-up period.

Use of continuous subcutaneous insulin infusion in patients with cystic fibrosis related diabetes: three case reports.

UNLABELLED: We used insulin pump therapy in three patients (two males and one female; age 5.5, 21 and 28.2 years, respectively) with CFRD and we reported the experience of 2 years of follow-up. In all the patients during the CSII treatment, the annual mean level of HbA1c reduced and the annual mean level of BMI increased, respected, the year before starting the CSII (in MDI treatment with 4 injections/day). The insulin requirements decreased during the CSII treatment and respected MDI treatment. During the CSII treatment, none of the patients exhibited episodes of DKA or severe hypoglycaemia. Only two episodes of lipohypertrophy and a slight local cutaneous inflammation were reported. CONCLUSIONS: The use of CSII in our patients with CFRD improves the metabolic control of diabetes and the nutritional status with no concomitant problems related to this treatment.

Lung transplantation for cystic fibrosis: 6-year follow-up.

Lung transplantation is currently the most effective means of improving survival and quality of life in patients with end-stage cystic fibrosis. In reviewing our 6-year experience we sought to evaluate complications and survival after sequential bilateral lung transplantation. Between October 1996 and October 2002, 114 patients with cystic fibrosis were referred to us from 15 Italian regional centers and 2 support centers for cystic fibrosis as possible candidates for lung transplantation. Of these 114 patients, 99 were included in the waiting list and 15 were refused. The mean time spent on the waiting list was 6.8+/-5.2 months (range 1 day-21 months) for those patients receiving lung transplantation, and 5.4+/-4.5 months (range 10 days-18 months) for those 35 patients who died while on the waiting list. A total 55 patients (6 children and 49 adults), mean age 25.6+/-6.6 years (range 9-52 years), 29 males, underwent bilateral sequential lung transplantation. One patient had a second transplantation 14 months after the first. The most frequent medical non-infective complications after transplantation were chronic renal failure (n=27 patients), diabetes (n=31), osteoporosis (n=17), arterial hypertension (n=14), seizures (n=4), transient cerebral ischaemia (n=1), and transient bilateral blindness (n=1). Bacterial lower airways respiratory infections with the organisms that colonized patients' airways before lung transplantation developed in 42 patients; cytomegalovirus (CMV) infection in 41; and opportunistic infections of the lung with Pneumocystis carinii in 3 patients. Cultures of sputum or bronchoalveolar lavage fluid grew Aspergillus fumigatus in nine patients; aspergillosis of right bronchial anastomosis developed in one patient and a lung infection in another. Another patient had a pulmonary infection secondary to Aspergillus niger. An average of 1.3 episodes of acute rejection developed per patient in the first 6 months after lung transplantation. Freedom from bronchiolitis obliterans syndrome was 95% at 1 year, 82.5% at 2 years, 70% at 3 years, and 65% at 4, 5 and 6 years. Actuarial survival rates were 80% at 1 month, 79% at 1 year, 74% at 2 years, 70% at 3 years and 58% at 4, 5 and 6 years. Ten patients (17.8%) died in the early postoperative period (1-30 days) for the following reasons: primary graft failure (n=4), multiorgan failure (n=3), Burkholderia cepacia sepsis (n=1), myocardial infarction (n=1), and pulmonary embolism (n=1). Mortality was accounted for by 9 patients (16%) who died from 9 to 43 months after lung transplantation, for the following reasons: P. carinii infection (n=2), bronchiolitis obliterans syndrome (n=4), A. fumigatus pulmonary infection (n=1), unknown cause (n=1) and suicide (n=1). In conclusion, the leading causes of morbidity after lung transplantation for cystic fibrosis are pulmonary bacterial infection and opportunistic infections. Bronchiolitis obliterans develops in more than half of lung transplant recipients who survive for more than 3 years and is an important cause of death in the late post transplantation period.