One-year glargine treatment can improve the course of lung disease in children and adolescents with cystic fibrosis and early glucose derangements

Targeting autophagy as a novel strategy for facilitating the therapeutic action of potentiators on ΔF508 cystic fibrosis transmembrane conductance regulator

Channel activators (potentiators) of cystic fibrosis (CF) transmembrane conductance regulator (CFTR), can be used for the treatment of the small subset of CF patients that carry plasma membrane-resident CFTR mutants. However, approximately 90% of CF patients carry the misfolded ΔF508-CFTR and are poorly responsive to potentiators, because ΔF508-CFTR is intrinsically unstable at the plasma membrane (PM) even if rescued by pharmacological correctors. We have demonstrated that human and mouse CF airways are autophagy deficient due to functional sequestration of BECN1 and that the tissue transglutaminase-2 inhibitor, cystamine, or antioxidants restore BECN1-dependent autophagy and reduce SQSTM1/p62 levels, thus favoring ΔF508-CFTR trafficking to the epithelial surface. Here, we investigated whether these treatments could facilitate the beneficial action of potentiators on ΔF508-CFTR homozygous airways. Cystamine or the superoxide dismutase (SOD)/catalase-mimetic EUK-134 stabilized ΔF508-CFTR at the plasma membrane of airway epithelial cells and sustained the expression of CFTR at the epithelial surface well beyond drug withdrawal, overexpressing BECN1 and depleting SQSTM1. This facilitates the beneficial action of potentiators in controlling inflammation in ex vivo ΔF508-CFTR homozygous human nasal biopsies and in vivo in mouse ΔF508-CFTR lungs. Direct depletion of Sqstm1 by shRNAs in vivo in ΔF508-CFTR mice synergized with potentiators in sustaining surface CFTR expression and suppressing inflammation. Cystamine pre-treatment restored ΔF508-CFTR response to the CFTR potentiators genistein, Vrx-532 or Vrx-770 in freshly isolated brushed nasal epithelial cells from ΔF508-CFTR homozygous patients. These findings delineate a novel therapeutic strategy for the treatment of CF patients with the ΔF508-CFTR mutation in which patients are first treated with cystamine and subsequently pulsed with CFTR potentiators.

Update on diagnosis and monitoring of cystic fibrosis-related diabetes mellitus (CFRD)

Cystic fibrosis (CF) is the most common recessive autosomal disease among Caucasian. Children with CF have benefitted from advances in medical and nutritional treatments, and this can be gleaned from the improvement in the survival of these patients. The increase in the survival rate brought with it the appearance of co-morbidities related to CF. Nowadays cystic fibrosis-related diabetes (CFRD) is considered the most common complication associated with CF. It can appear as early as infancy or adolescence, and its prevalence can be as high as 50% in adult patients. Because of its high prevalence, difficulties in early detection and the risks involved, in recent years several studies and consensuses have focused on this condition, adding information about the epidemiology, pathophysiology, prognosis and treatment of CFRD. The main aspects of these new concepts, as well as the current recommendations for its diagnosis and follow-up, will be presented in this study.

Low glycaemic index dietary interventions in youth with cystic fibrosis: a systematic review and discussion of the clinical implications

A systematic review was conducted to assess what is known about the effect of low glycaemic index (GI) diets on glycaemic control, weight and quality of life in youth with cystic fibrosis (CF). Eligibility criteria were systematic reviews, randomised and non-randomised trials of low GI dietary interventions in CF. Outcomes examined were glycaemic control, quality of life, anthropometry and respiratory function. Reference lists were manually searched and experts in the field were consulted. Four studies met the eligibility criteria; two were excluded because they did not include data on any of the outcomes. The remaining two were studies that examined GI secondary to any other intervention: one used GI as a factor in enteral feeds and the other incorporated low GI dietary education into its treatment methodology. There is insufficient evidence to recommend use of low GI diets in CF. Since there is evidence to support use of low GI diets in type 1, type 2 and gestational diabetes, low GI diets should be tested as an intervention for CF. The potential risks and benefits of a low GI diet in CF are discussed.

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.

Cystic fibrosis related diabetes (CFRD)--the end stage of progressive insulin deficiency

In cystic fibrosis, gradual pancreatic destruction causes progressive insulin deficiency, culminating in cystic fibrosis related diabetes (CFRD). As a consequence of insulin deficiency, elevated glucose levels can be detected (well before the diagnosis of CFRD), by continuous ambulatory subcutaneous interstitial fluid glucose monitoring or 30-min sampled oral glucose tolerance test (OGTT). Current diagnostic criteria for CFRD (based on 0 and 120-min OGTT blood glucose levels) were originally designed to forecast microvascular disease in type 2 diabetes, rather than CF-specific outcomes such as declining weight or lung function. In CF, decline in either weight or lung function predicts early mortality. Both may precede the diagnosis of CFRD by several years. Insulin, a potent anabolic hormone, is recommended treatment for CFRD, but use in earlier stages of insulin deficiency is not established. Conventional dosing (with four or more insulin injections per day) is burdensome and carries substantial risk of hypoglycemia. However, recent uncontrolled trials suggest that once-daily injection of intermediate or long-acting insulin improves weight and lung function, with minimal hypoglycemia risk, in CFRD and also in early insulin deficiency. It is plausible that insulin may be of greater benefit to respiratory function when given prior to the diagnosis of CFRD, after which structural lung disease may be irreversible. It is also plausible that early insulin treatment may prolong the lifespan of the remaining insulin-secreting β-cells. Randomized controlled trials are now needed to determine whether or not current clinical practice should be altered toward the earlier commencement of insulin in CF.

Long-term benefits in lung function and nutritional status of strict metabolic control of cystic fibrosis-related diabetes

Cystic fibrosis related diabetes (CFRD) is a strong determinant for lung function decline and increased mortality. Insulin treatment of CFRD is reportedly beneficial for this situation. We report on the long-term impact of insulin treatment of CFRD on pulmonary function and nutritional status in a CF male patient since diagnosis of diabetes. We report the case of a patient diagnosed with CF at the age of 16. Two years later, he experienced a rapidly evolving decrease in pulmonary function, some months later criteria were met warranting lung transplantation. Concomitantly, he was diagnosed with CFRD and insulin therapy was started. Lung function (spirometry), nutritional status (body mass index) and metabolic control (HbA(1c)) were determined every 3 months. After the introduction of insulin treatment, pulmonary function and nutritional status progressively improved and good glycemic control was achieved. The significant and sustained improvement in pulmonary function allowed for the patient's withdrawal from the lung transplantation program within 4 months, a situation which has been maintained until now, 8 years later. The long follow-up of our patient documents the rapid and prolonged beneficial effect of proper metabolic control of CFRD on the respiratory deterioration in CF.

Low-dose insulin therapy in patients with cystic fibrosis and early-stage insulinopenia prevents deterioration of lung function: a 3-year prospective study

Cystic fibrosis related diabetes (CFRD) is an insulinopenic condition. We aimed to detect insulinopenia early and to evaluate the impact of low dose insulin on nutritional status and forced expiratory volume in first second (FEV1). Out of 142 cystic fibrosis patients (CFpts) older than 10 years, 28 with abnormal oral glucose tolerance test in spite of normal fasting glycemia were found to have decreased first phase insulin release and started low dose insulin therapy (median age 15.4 years). Sex and age matched CFpts with normal glucose tolerance (NGT) were observed for comparison. Whereas nutritional status improved following 3 years of insulin administration, FEV1 stabilized in insulin-treated insulinopenic subjects (73.8 +/- 4.3% vs. 73.5 +/- 4.4%), but decreased in the parallel group with NGT who remained without insulin treatment (71.1 +/- 3.8% vs. 61.0 +/- 4.0%; p = 0.001). We conclude that low dose insulin improves nutritional status and stabilizes pulmonary functions. Regular estimation of stimulated insulin secretion in CFpts may allow optimizing treatment.

Oral glucose tolerance testing in children with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) related diabetes is the most common comorbidity in persons with CF. International Society for Pediatric and Adolescent Diabetes (ISPAD) guidelines recommend annual oral glucose tolerance testing (OGTT) screening starting at age 10. The OGTT might be recommended in younger children if, as in adults, it provided clinically relevant prognostic information. A database review was performed to determine whether OGTT findings in children with CF predict subsequent clinical course.

METHODS

A retrospective matched-pair cohort study was based on OGTTs performed during 1998-2003. Children aged 6-9 were classified as having normal glucose tolerance (NGT) or abnormal glucose tolerance (AGT). Children with AGT were matched by age and gender to those with NGT. Clinical status was assessed at baseline and 5 yr later. In a separate investigation, diabetes and prior AGT status of children aged 10-18 were used to assess predictions derived from the cohort study.

RESULTS

In 1998-2003, 39 of 94 children had AGT. Of these, 31 had sufficient follow-up data to be included. Both at baseline and 5 yr later there was no significant difference in height, weight, body mass index (BMI) or lung function between AGT and NGT. Diabetes developed in 13 AGT (42%) and one NGT (3%) [odds ratio (OR) 11, p = 0.0009]. Age of diabetes onset was 12 ± 1 yr in boys and 11 ± 1 yr in girls, compared to approximately 23 yr in the general CF population. Fifteen current children age 10-18 who had AGT before age 10 have diabetes, close to the prediction of 19.

CONCLUSIONS

AGT in children with CF age 6-9 yr identifies those at high risk for progression to early onset diabetes.

Recent trends in cystic fibrosis-related diabetes

PURPOSE OF REVIEW

To provide an updated literature review highlighting important aspects of cystic fibrosis-related diabetes (CFRD) including epidemiology, pathogenesis, complications, screening, and management.

RECENT FINDINGS

Although CFRD continues to be associated with increased rates of mortality in the cystic fibrosis (CF) population, this has improved over the past several years, and the previous sex difference is no longer present. Recent studies support that CFRD is primarily caused by insulin deficiency due to loss of beta cells, which may occur via a number of mechanisms including oxidative stress. Aggressive screening programs with oral-glucose tolerance testing and early treatment with insulin for patients with CFRD with or without fasting hyperglycemia have led to improvements in nutritional states and lung function. Oral agents do not appear to be effective in CFRD.

SUMMARY

CFRD is the most common comorbidity in the CF population and is associated with microvascular complications and protein catabolism leading to worse health outcomes. Recognition of glycemic abnormalities through aggressive screening has led to improvements in nutritional status, pulmonary function, and mortality rates.

Cystic fibrosis-related diabetes in children--gaps in the evidence?

As the life span of patients with cystic fibrosis has increased, so has the prevalence of cystic fibrosis-related diabetes mellitus. However, screening practices for cystic fibrosis-related diabetes mellitus vary widely, which affects accurate estimates of the health burden of this comorbidity. The management of prediabetes and hyperglycemia is an increasingly important aspect of care in patients with cystic fibrosis, but few studies have specifically addressed the management of cystic fibrosis-related diabetes mellitus. Previous studies support the use of insulin for the treatment of patients with this disorder, but the evidence for its use in patients with cystic fibrosis and impaired glucose tolerance is poor. Nutritional management is currently guided by dietary recommendations for individuals with cystic fibrosis, with little evidence specific to the dietary management of patients with cystic fibrosis-related diabetes mellitus. Additionally, microvascular complications have become more frequent as a result of the rise in life expectancy of these patients, yet to date no intervention studies have addressed prevention or management of diabetic complications in patients with cystic fibrosis. A strong evidence base is needed to guide the management of patients with cystic fibrosis-related diabetes mellitus and its complications.

Insulin therapy to improve BMI in cystic fibrosis-related diabetes without fasting hyperglycemia: results of the cystic fibrosis related diabetes therapy trial

OBJECTIVE

Cystic fibrosis-related diabetes (CFRD) without fasting hyperglycemia (CFRD FH-) is not associated with microvascular or macrovascular complications, leading to controversy about the need for treatment. The Cystic Fibrosis Related Diabetes Therapy (CFRDT) Trial sought to determine whether diabetes therapy improves BMI in these patients.

RESEARCH DESIGN AND METHODS

A three-arm multicenter randomized trial compared 1 year of therapy with premeal insulin aspart, repaglinide, or oral placebo in subjects with cystic fibrosis who had abnormal glucose tolerance.

RESULTS

One hundred adult patients were enrolled. Eighty-one completed the study, including 61 with CFRD FH- and 20 with severly impaired glucose tolerance (IGT). During the year before therapy, BMI declined in all groups. Among the group with CFRD FH-, insulin-treated patients lost 0.30 +/- 0.21 BMI units the year before therapy. After 1 year of insulin therapy, this pattern reversed, and they gained 0.39 +/- 21 BMI units (P = 0.02). No significant change in the rate of BMI decline was seen in placebo-treated patients (P = 0.45). Repaglinide-treated patients had an initial significant BMI gain (0.53 +/- 0.19 BMI units, P = 0.01), but this effect was not sustained. After 6 months of therapy they lost weight so that by 12 months there was no difference in the rate of BMI change during the study year compared with the year before (P = 0.33). Among patients with IGT, neither insulin nor repaglinide affected the rate of BMI decline. No significant differences were seen in the rate of lung function decline or the number of hospitalizations in any group.

CONCLUSIONS

Insulin therapy safely reversed chronic weight loss in patients with CFRD FH-.