Prostaglandin E2 and phagocytosis of inhaled particulate matter by airway macrophages in cystic fibrosis.

BACKGROUND: Exposure to particulate matter (PM) air pollution is associated with adverse health outcomes in children with cystic fibrosis (CF). Airway macrophages (AM) phagocytose and retain inhaled PM in vivo, and the area of carbon in AM reflects both inhaled PM dose and phagocytic function. Since airway prostaglandin-E2 (PGE2) is increased in CF, and PGE2 suppresses AM phagocytosis, we sought evidence for PGE2-mediated suppression of AM phagocytosis of inhaled carbonaceous PM in CF. METHODS: After informed consent, urine was obtained from 20 controls and 24 CF children. In the subgroup of older children, at least one induced sputum was done in 20 controls and 19 CF children. Urinary tetranor PGEM, the major metabolite of PGE2, and sputum PGE2 were measured by mass spectrometry. The area of carbon in AM was determined by image analysis. Exposure to PM was assessed by modelling and personal monitoring. The effect of either PGE2 or CF sputum supernatant on phagocytosis of diesel exhaust particle (DEP) by AM was assessed in vitro. Data were analysed by t-test. RESULTS: Both urinary tetranor PGEM (P<0.05), and sputum PGE2 (P<0.05) were increased in CF . Despite no difference in PM exposure between groups, the area of phagocytosed carbon by AM was decreased in children with CF (P<0.01). PGE2 suppressed phagocytosis of DEP by AM from both controls and CF (P<0.0001). CF sputum supernatant suppressed phagocytosis of DEP by AM (P<0.0001) in a PGE2-dependent manner. CONCLUSION: Increased PGE2 in the CF airway suppresses phagocytosis of inhaled PM by AM.

Urinary Exosomes of Patients with Cystic Fibrosis Unravel CFTR-Related Renal Disease.

Background: The prevalence of chronic kidney disease is increased in patients with cystic fibrosis (CF). The study of urinary exosomal proteins might provide insight into the pathophysiology of CF kidney disease. Methods: Urine samples were collected from 19 CF patients (among those 7 were treated by cystic fibrosis transmembrane conductance regulator (CFTR) modulators), and 8 healthy subjects. Urine exosomal protein content was determined by high resolution mass spectrometry. Results: A heatmap of the differentially expressed proteins in urinary exosomes showed a clear separation between control and CF patients. Seventeen proteins were upregulated in CF patients (including epidermal growth factor receptor (EGFR); proteasome subunit beta type-6, transglutaminases, caspase 14) and 118 were downregulated (including glutathione S-transferases, superoxide dismutase, klotho, endosomal sorting complex required for transport, and matrisome proteins). Gene set enrichment analysis revealed 20 gene sets upregulated and 74 downregulated. Treatment with CFTR modulators yielded no significant modification of the proteomic content. These results highlight that CF kidney cells adapt to the CFTR defect by upregulating proteasome activity and that autophagy and endosomal targeting are impaired. Increased expression of EGFR and decreased expression of klotho and matrisome might play a central role in this CF kidney signature by inducing oxidation, inflammation, accelerated senescence, and abnormal tissue repair. Conclusions: Our study unravels novel insights into consequences of CFTR dysfunction in the urinary tract, some of which may have clinical and therapeutic implications.

Urine lipoarabinomannan as a marker for low-risk of NTM infection in the CF airway.

BACKGROUND: Individuals with Cystic fibrosis (CF) are the most vulnerable population for pulmonary infection with nontuberculous mycobacteria (NTM). Screening, diagnosis, and assessment of treatment response currently depend on traditional culture techniques, but sputum analysis for NTM in CF is challenging, and associated with a low sensitivity. The cell wall lipoarabinomannan (LAM), a lipoglycan found in all mycobacterial species, and has been validated as a biomarker in urine for active Mycobacterium tuberculosis infection. METHODS: Urine from a CF cohort (n = 44) well-characterized for NTM infection status by airway cultures was analyzed for LAM by gas chromatography/mass spectrometry. All subjects with positive sputum cultures for NTM had varying amounts of LAM in their urine. No LAM was detected in subjects who never had a positive culture (14/45). One individual initially classified as NTM sputum negative subsequently developed NTM disease 657 days after the initial urine LAM testing. Repeat urine LAM testing turned positive, correlating to her positive NTM status. Subjects infected with subspecies of M. abscessus had greater LAM quantities than those infected with M. avium complex (MAC). There was no correlation with disease activity or treatment status and LAM quantity. A TB Capture ELISA using anti-LAM antibodies demonstrated very poor sensitivity in identifying individuals with positive NTM sputum cultures. CONCLUSION: These findings support the conclusion that urine LAM related to NTM infection may be a useful screening test to determine patients at low risk for having a positive NTM sputum culture, as part of a lifetime screening strategy in the CF population.

A randomised controlled trial of rosuvastatin for the prevention of aminoglycoside-induced kidney toxicity in children with cystic fibrosis.

The PROteKT study tested the hypothesis that rosuvastatin can inhibit aminoglycoside-induced nephrotoxicity in children with Cystic Fibrosis (CF). This open label, parallel group, randomised controlled trial recruited children and young people aged 6 to 18 years with CF at 13 paediatric CF treatment centres in the UK. Participants were randomised equally to either receive oral rosuvastatin (10 mg once daily) or no intervention (control) throughout clinically indicated treatment with intravenous tobramycin. The primary outcome was the difference between the groups in mean fold-change in urinary Kidney Injury Molecule-1 (KIM-1). Fifty (rosuvastatin n = 23, control n = 27) participants were recruited between May 2015 and January 2017. Primary outcome data was available for 88% (rosuvastatin n = 20, control n = 24). The estimated mean treatment difference in the geometric mean-fold change of normalised KIM-1 was 1.08 (95% CI 0.87-1.35, p = 0.48). In total there were 12 adverse reactions, all mild, reported by five participants randomised to rosuvastatin, and one serious adverse event in each group. Whilst no protective effect of rosuvastatin was seen, there was a lower than expected level of nephrotoxicity in the cohort. Therefore, we can neither confirm nor refute the hypothesis that rosuvastatin protects against aminoglycoside nephrotoxicity.

Pharmacokinetics of colistin after nebulization or intravenous administration of colistin methanesulphonate (Colimycin®) to cystic fibrosis patients.

OBJECTIVES: Colistin, administered as the prodrug colistin methanesulphonate (CMS), is an antibiotic frequently administered as aerosol in cystic fibrosis (CF) patient. Our aim was to assess the plasma PK of colistin in CF patients treated with CMS administered intravenously or as aerosol and to compare these results with those previously reported in healthy volunteers. METHODS: Six CF patients were included, CMS and colistin concentrations were measured in plasma, urine and sputum. Either after single intravenous administration of 2 Million International Unit (MIU) or after repeated nebulizations of 2 MIU of CMS. PK of CMS and colistin were assessed by a mixed effect modeling approach. RESULTS: Renal clearance of CMS was lower in CF patients compared to that previously reported in healthy volunteers (64.3 mL/min (RSE = 15%) vs. 103 mL/min (RSE = 8%)). However, apparent clearance of colistin was higher in CF patients compared to healthy volunteers (124 mL/min (RSE = 13%) vs. 48.7 mL/min (RSE = 15%)), resulting in reduced systemic exposure to colistin (dose normalized AUC (2 MIU) of 7.4 h.mg/L/MIU vs. 11.2 h.mg/L/MIU). After repeated nebulizations, colistin concentrations were very low in plasma (<0.21 mg/L). CONCLUSIONS: Although our study suggests a lower median dose normalized colistin plasma concentrations in CF patients compared with healthy controls, this difference was not significant and a larger study is needed to substantiate this.

Urinary metabolomics reveals unique metabolic signatures in infants with cystic fibrosis.

BACKGROUND: Biologic pathways and metabolic mechanisms underpinning early systemic disease in cystic fibrosis (CF) are poorly understood. The Baby Observational and Nutrition Study (BONUS) was a prospective multi-center study of infants with CF with a primary aim to examine the current state of nutrition in the first year of life. Its secondary aim was to prospectively explore concurrent nutritional, metabolic, respiratory, infectious, and inflammatory characteristics associated with early CF anthropometric measurements. We report here metabolomics differences within the urine of these infants as compared to infants without CF. METHODS: Urine metabolomics was performed for 85 infants with predefined clinical phenotypes at approximately one year of age enrolled in BONUS via Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS). Samples were stratified by disease status (non-CF controls (n = 22); CF (n = 63, All-CF)) and CF clinical phenotype: respiratory hospitalization (CF Resp, n = 22), low length (CF LL, n = 23), and low weight (CF LW, n = 15). RESULTS: Global urine metabolomics profiles in CF were heterogeneous, however there were distinct metabolic differences between the CF and non-CF groups. Top pathways altered in CF included tRNA charging and methionine degradation. ADCYAP1 and huntingtin were identified as predicted unique regulators of altered metabolic pathways in CF compared to non-CF. Infants with CF displayed alterations in metabolites associated with bile acid homeostasis, pentose sugars, and vitamins. CONCLUSIONS: Predicted metabolic pathways and regulators were identified in CF infants compared to non-CF, but metabolic profiles were unable to discriminate between CF phenotypes. Targeted metabolomics provides an opportunity for further understanding of early CF disease. TRIAL REGISTRATION: United States ClinicalTrials.Gov registry NCT01424696 (clinicaltrials.gov).

Urinary tract stones in cystic fibrosis.

Urinary tract stones are a common problem in a general population but increasingly so in cystic fibrosis (CF) patients as survival improves. Mechanisms of stone formation are discussed, particularly those unique to CF patients. Modalities of treatment and the decision making process in this choice is outlined as well as possible future preventative strategies.

Urinary Biomarkers of Aminoglycoside-Induced Nephrotoxicity in Cystic Fibrosis: Kidney Injury Molecule-1 and Neutrophil Gelatinase-Associated Lipocalin.

Aminoglycosides are commonly used for the treatment of pulmonary exacerbations in patients with cystic fibrosis (CF). However, they are potentially nephrotoxic. This prospective observational cohort study aimed to investigate the potential validity of two urinary renal biomarkers, Kidney Injury Molecule-1 (KIM-1) and Neutrophil Gelatinase-associated Lipocalin (NGAL), in identifying aminoglycoside-induced nephrotoxicity in children with CF. Children and young adults up to 20 years of age with a confirmed diagnosis of CF were recruited from ten United Kingdom hospitals. Participants provided urine samples for measurement of KIM-1 and NGAL concentrations, at baseline, at regular outpatient appointments, and before, during and after exposure to clinically-indicated treatment with the aminoglycoside tobramycin. 37/158 patients recruited (23.4%) received at least one course of IV tobramycin during the study. The median peak fold-change during tobramycin exposure for KIM-1 was 2.28 (IQR 2.69) and 4.02 (IQR 7.29) for NGAL, in the absence of serum creatinine changes. Baseline KIM-1 was positively associated with cumulative courses of IV aminoglycosides (R2 = 0.11; ß = 0.03; p < 0.0001). KIM-1, in particular, may be a useful, non-invasive, biomarker of acute and chronic proximal tubular injury associated with exposure to aminoglycosides in patients with CF, but its clinical utility needs to be further evaluated in prospective studies.

Elevated prostaglandin E metabolites and abnormal plasma fatty acids at baseline in pediatric cystic fibrosis patients: a pilot study.

BACKGROUND: Airway inflammation is a significant contributor to the morbidity of cystic fibrosis (CF) disease. One feature of this inflammation is the production of oxygenated metabolites, such as prostaglandins. Individuals with CF are known to have abnormal metabolism of fatty acids, typically resulting in reduced levels of linoleic acid (LA) and docosahexaenoic acid (DHA). METHODS: This is a randomized, double-blind, cross-over clinical trial of DHA supplementation with endpoints of plasma fatty acid levels and prostaglandin E metabolite (PGE-M) levels. Patients with CF age 6-18 years with pancreatic insufficiency were recruited. Each participant completed 3 four-week study periods: DHA at two different doses (high dose and low dose) and placebo with a minimum 4 week wash-out between each period. Blood, urine, and exhaled breath condensate (EBC) were collected at baseline and after each study period for measurement of plasma fatty acids as well as prostaglandin E metabolites. RESULTS: Seventeen participants were enrolled, and 12 participants completed all 3 study periods. Overall, DHA supplementation was well tolerated without significant adverse events. There was a significant increase in plasma DHA levels with supplementation, but no significant change in arachidonic acid (AA) or LA levels. However, at baseline, AA levels were lower and LA levels were higher than previously reported for individuals with CF. Urine PGE-M levels were elevated in the majority of participants at baseline, and while levels decreased with DHA supplementation, they also decreased with placebo. CONCLUSIONS: Urine PGE-M levels are elevated at baseline in this cohort of pediatric CF patients, but there was no significant change in these levels with DHA supplementation compared to placebo. In addition, baseline plasma fatty acid levels for this cohort showed some difference to prior reports, including higher levels of LA and lower levels of AA, which may reflect changes in clinical care, and consequently warrants further investigation.

Evaluation of a Once/Day Tobramycin Regimen to Achieve Target Concentrations in Adult Patients with Cystic Fibrosis.

STUDY OBJECTIVE: To evaluate the success of an initial tobramycin dosing regimen to achieve target peak and trough concentrations in adult patients with pulmonary exacerbations of cystic fibrosis (CF). DESIGN: Retrospective single-center medical record review. SETTING: Large tertiary care academic medical center. PATIENTS: A total of 186 patient encounters where 112 patients with CF were treated for acute pulmonary exacerbations with 10 mg/kg/day of tobramycin between January 1, 2009, and December 5, 2014. MEASUREMENTS AND MAIN RESULTS: Baseline demographics, clinical characteristics, tobramycin data, and pharmacokinetic variables were collected. The primary outcome evaluated the success of the initial tobramycin dosing regimen in attaining the target peak concentration. Secondary end points were achievement of the target trough concentration, achievement of combined peak and trough targets, and incidence of nephrotoxicity. Bivariate and multivariate analyses were performed to evaluate factors associated with achieving target concentrations. Of the 186 patient encounters, 41% achieved the target peak with the first dosing regimen, 62% achieved a target trough, and 23% achieved the target peak and trough. Nephrotoxicity occurred in 10% of patient encounters. A body mass index (BMI) of 18.5-24.9 kg/m(2) was associated with higher odds of meeting the target peak compared with a BMI lower than 18.5 kg/m(2) (odds ratio [OR] 24.5; 95% confidence interval [CI] 5.2-117.2). Conversely, a BMI of 18.5-24.9 kg/m(2) was associated with lower odds of attaining the target trough compared with a BMI lower than 18.5 kg/m(2) (OR 0.16; 95% CI 0.05-0.56). Higher volume of distribution and elimination rate constants (Kel ) were associated with significantly lower odds of achieving the target peak. In addition, higher Kel values were associated with significantly higher odds of achieving the target trough. CONCLUSIONS: The current initial tobramycin regimen did not achieve target serum tobramycin concentrations reliably. Optimization of the initial CF tobramycin dosing regimen is warranted.

Pseudomonas aeruginosa quorum sensing molecules correlate with clinical status in cystic fibrosis.

Pseudomonas aeruginosa produces quorum sensing signal molecules that are potential biomarkers for infection.A prospective study of 60 cystic fibrosis patients with chronic P. aeruginosa, who required intravenous antibiotics for pulmonary exacerbations, was undertaken. Clinical measurements and biological samples were obtained at the start and end of the treatment period. Additional data were available for 29 of these patients when they were clinically stable.Cross-sectionally, quorum sensing signal molecules were detectable in the sputum, plasma and urine of 86%, 75% and 83% patients, respectively. They were positively correlated between the three biofluids. Positive correlations were observed for most quorum sensing signal molecules in sputum, plasma and urine, with quantitative measures of pulmonary P. aeruginosa load at the start of a pulmonary exacerbation. Plasma concentrations of 2-nonyl-4-hydroxy-quinoline (NHQ) were significantly higher at the start of a pulmonary exacerbation compared to clinical stability (p<0.01). Following the administration of systemic antibiotics, plasma 2-heptyl-4-hydroxyquinoline (p=0.02) and NHQ concentrations (p<0.01) decreased significantly.In conclusion, quorum sensing signal molecules are detectable in cystic fibrosis patients with pulmonary P. aeruginosa infection and are positively correlated with quantitative measures of P. aeruginosa. NHQ correlates with clinical status and has potential as a novel biomarker for P. aeruginosa infection.

Capillary electromigration techniques as tools for assessing the status of vitamins A, C and E in patients with cystic fibrosis.

The purpose of this work is the evaluation of the nutritional status of patients with cystic fibrosis (CF), based on the level of vitamin C in urine and vitamins A and E in serum, using the fast, selective and fully automated micellar electrokinetic capillary chromatographic (MEKC) and microemulsion electrokinetic capillary chromatographic (MEEKC) methods. The optimization of parameters affecting the electrophoretic separation provided adequate separation of the analytes of interest in the short time of 8 min (MEKC) and 20 min (MEEKC). The developed methods were practical applications to evaluate the levels of vitamins A, C and E in real samples from 28 children suffering from cystic fibrosis and from 10 healthy volunteers. Based on the mean concentration values obtained in the two groups, it can be seen that the levels of each vitamin were lower in patients with CF than in healthy volunteers. In the case of vitamin E, these differences in both groups were statistically significant, while the disproportion of concentrations of vitamins A and C in both the studied groups were not so relevant. On the other hand, a principal component analysis (PCA) confirmed that in some patients with CF the concentration of vitamin A was significantly lower than in the control group. Thus, the future evaluation of the status of fat-soluble vitamins in the longer term for the evaluation of the nutritional status of patients with CF should be continued. The presented CE methods can become useful tools for the evaluation of the nutritional status of patients with CF.

Quantification of major urinary metabolites of PGE2 and PGD2 in cystic fibrosis: correlation with disease severity.

Cystic fibrosis transmembrane conductance (CFTR) alterations are involved in the overproduction of prostaglandins (PG) in CF in vitro. We assessed the relationship between PGE-M and PGD-M urinary metabolites of PGE2 and PGD2 and CF severity. Twenty-four controls and 35 CF patients were recruited. PGE-M and PGD-M levels were measured by liquid chromatography/mass spectrometry and results were expressed as median and 25th-75th interquartile of ng/mg creatinine (Cr). PGE-M (15.63; 9.07-43.35ng/mg Cr) and PGD-M (2.16; 1.43-3.53ng/mg Cr) concentrations were higher in CF than in controls: PGE-M, (6.63; 4.35-8.60ng/mg Cr); PGD-M (1.23; 0.96-1.54ng/mg Cr). There was no correlation between metabolite levels and spirometric values. Patients with pancreatic insufficiency (n=29) had higher PGE-M levels (19.09; 9.36-52.69ng/mg Cr) than those with conserved function (n=6) (9.61; 5.78-14.34ng/mg Cr). PGE-M levels were associated with genotype severity: mild (7.14; 5.76-8.76, n=8), moderate (16.67; 13.67-28.62ng/mg Cr, n=5) and severe (22.82; 10.67-84.13ng/mg Cr). Our study confirms the key role of CFTR in the regulation of the cyclooxygenase pathway of arachidonic acid metabolism found in in vitro studies.

Iodine deficiency and subclinical hypothyroidism are common in cystic fibrosis patients.

BACKGROUND: Disorders of thyroid function have been inconsistently described in cystic fibrosis (CF) patients and in CF transmembrane regulator protein knockout animals. The literature lacks reports on iodine status of CF individuals. We hypothesize, that iodine deficiency is common in CF and account for abnormal thyroid function in CF patients. METHODS: We investigated 129 children, adolescents, and adults with CF, who were living in the northern part of Bavaria/Germany. Malnutrition and lung function were analyzed. Urinary iodine excretion, TSH (thyroid-stimulating hormone), and ft4 (free thyroxine) were measured and set in relation to population-based, age-adjusted reference ranges. RESULTS: Subclinical hypothyroidism (normal fT4, elevated TSH) was found in 11.6% of subjects, and iodine deficiency in 83.7%. No correlations were found with age, BMI, status of malnutrition, or lung function. CONCLUSION: Dramatic iodine deficiency was found in our cohort of CF patients. This condition can cause subclinical hypothyroidism; therefore, an individual iodine supplementation program is necessary and should be started immediately.

CFTR is involved in the fine tuning of intracellular redox status: physiological implications in cystic fibrosis.

Adaptation to hypoxia is an essential physiological response to decrease in tissue oxygenation. This process is primarily under the control of transcriptional activator hypoxia-inducible factor (HIF1). A better understanding of the intracellular HIF1 stabilization pathway would help in management of various diseases characterized by anemia. Among human pathologies, cystic fibrosis disease is characterized by a chronic anemia that is inadequately compensated by the classical erythroid response mediated by the HIF pathway. Because the kidney expresses CFTR and is a master organ involved in the adaptation to hypoxia, we used renal cells to explore the relationship between CFTR and the HIF1-mediated pathway. To monitor the adaptive response to hypoxia, we engineered a hypoxia-induced fluorescent reporter system to determine whether CFTR modulates hypoxia-induced HIF1 stabilization. We show that CFTR is a regulator of HIF stabilization by controlling the intracellular reactive oxygen species (ROS) level through its ability to transport glutathione (a ROS scavenger) out of the cell. Moreover, we demonstrated in a mouse model that both the pharmacological inhibition and the ΔF508 mutation of CFTR lead to an impairment of the adaptive erythroid response to oxygen deprivation. We conclude that CFTR controls HIF stabilization through control of the level of intracellular ROS that act as signaling agents in the HIF-1 pathway.

Oral magnesium supplementation in children with cystic fibrosis improves clinical and functional variables: a double-blind, randomized, placebo-controlled crossover trial.

BACKGROUND: Magnesium is one of the most important minerals in the body. Although some studies reported that patients with cystic fibrosis (CF) lack magnesium, no international study has assessed the importance of oral magnesium supplementation in CF patients. OBJECTIVE: We prospectively investigated the long-term effect of oral magnesium supplementation on respiratory muscle strength by using manuvacuometry and the Shwachman-Kulczycki (SK) score among children and adolescents with CF. DESIGN: This double-blind, randomized, placebo-controlled crossover study included 44 CF patients (aged 7-19 y; 20 males) who were randomly assigned to receive magnesium (n = 22; 300 mg/d) or placebo (n = 22) for 8 wk with a 4-wk washout period between trials. All patients were undergoing conventional treatment of CF. The experimental protocol included clinical evaluation, assessment of urinary concentration of magnesium, and manuvacuometric measurements [maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP)]. MIP was the primary outcome. RESULTS: Urinary magnesium increased after the administration of magnesium (change: 36.38 mg/d after magnesium compared with 0.72 mg/d after placebo; P < 0.001). Moreover, MIP and MEP significantly improved only after magnesium administration (change in MIP: 11% predicted after magnesium compared with 0.5% predicted after placebo; change in MEP: 11.9% predicted after magnesium compared with 0.8% predicted after placebo; P < 0.001 for both). Magnesium administration had a beneficial effect on clinical variables assessed by the SK score (change: 4.48 points after magnesium compared with -1.30 points after placebo; P < 0.001). CONCLUSION: Oral magnesium supplementation helped improve both the SK score and respiratory muscle strength in pediatric patients with CF.

Urinary desmosine: a biomarker of structural lung injury during CF pulmonary exacerbation.

RATIONALE: Cystic fibrosis (CF) lung disease is characterized by structural changes and remodeling in airway architecture and lung parenchyma. Neutrophilic inflammation and infection lead to injury and breakdown of airway matrix constituents, including elastin. The non-invasive measurement of urinary desmosine (UDes), a breakdown product of elastin, may be reflective of ongoing lung injury and may serve as a biomarker of active short-term damage during pulmonary exacerbation. Our objectives were to measure desmosine in the urine of CF patients hospitalized for treatment of a pulmonary exacerbation and to explore the correlation between desmosine concentration and other markers of clinical improvement, including lung function and inflammatory mediators. METHODS: Urine and blood samples plus lung function measurements were collected at up to three points during hospitalization for treatment of a CF pulmonary exacerbation. We used a repeated measures model, adjusted for age and time between measurements, to compare log transformed urine desmosine concentrations across multiple time points and to correlate those concentrations with related clinical variables. Change in UDes concentration was investigated using a statistical model that incorporated normalization factors to account for variations in urinary concentration. RESULTS: Desmosine was measured by radioimmunoassay (RIA) in 155 spot urine samples from 53 CF patients hospitalized for 63 pulmonary exacerbations (range of results: 0-235 pmol Des/ml). Specific gravity (SG) adjusted UDes concentration decreased significantly during admission for CF pulmonary exacerbation, P < 0.01 (average length of stay = 11 days). No correlation was observed between UDes concentration and lung function or inflammatory markers. CONCLUSIONS: UDes decreased significantly following treatment for an acute pulmonary exacerbation and may be a useful biomarker of short-term injury to the CF lung. Further investigation is needed to evaluate the utility of UDes concentration in the long-term progression of CF lung disease.

Microalbuminuria in patients with cystic fibrosis.

OBJECTIVE: We previously found that microalbuminuria (MA) is present in 14% of patients with long-standing cystic fibrosis-related diabetes (CFRD). However, others have reported much higher rates of MA in CF patients with and without diabetes (32-67%), suggesting this test is not sufficiently specific for diabetic nephropathy screening in CF. We investigated transient (TMA) and persistent (PMA) microalbuminuria in CF patients to resolve these contradictory findings. RESEARCH DESIGN AND METHODS: We reviewed 1,449 outpatient urinary albumin measurements from 467 patients aged ≥10 years, which were collected over a decade. TMA was defined as a single episode of MA that subsequently was resolved. PMA was defined as two consecutive or two out of three consecutive measurements in the MA range. RESULTS: The prevalence of TMA that subsequently was resolved in CF patients was similar to the general population. It was found in 7.6% of patients, including 5% of youth (aged 10-17 years) and 9% of adults. PMA was found in 6.1% of the overall CF population, including 2% of youth and 8% of adults. The odds of PMA were increased sevenfold in patients with CFRD (95% CI 2.5-20, P=0.0002) and 48-fold in patients with both CFRD and organ transplant (95% CI 13-177, P<0.0001). The five patients with PMA in the absence of CFRD or transplant included two youths with presumed benign orthostatic MA and three adults with hypertension. CONCLUSIONS: The spot urine albumin-to-creatinine ratio is specific enough to be a valid screening test for diabetic kidney disease in CFRD.

The applicability of urinary creatinine as a method of specimen normalization in the cystic fibrosis population.

BACKGROUND: Urine specimens are commonly used in biomarker research. Urinary creatinine (UCr) is often used to adjust for urine analyte concentration. We aim to explore the applicability of UCr as a normalization method in a cystic fibrosis (CF) population during hospitalization. METHODS: Multiple spot urine samples were collected from CF patients hospitalized for a pulmonary exacerbation. Single spot specimens were obtained from asthmatics and healthy children for comparison. The assumptions and implications from the use of UCr as a normalization factor for urinary desmosine measurements were investigated. RESULTS: UCr differed significantly across disease groups and decreased significantly over time in the CF population. Differing results were obtained when contrasting normalization by UCr with specific gravity. CONCLUSIONS: UCr levels are not completely attributable to simply variations in urine concentration. Analysis of urinary biomarker measurements should be initiated with an understanding of the relative effects of the normalization process on the results.

Alveolar inflammation in cystic fibrosis.

BACKGROUND: In infected lungs of the cystic fibrosis (CF) patients, opportunistic pathogens and mutated cystic fibrosis transmembrane conductance regulator protein (CFTR) contribute to chronic airway inflammation that is characterized by neutrophil/macrophage infiltration, cytokine release and ceramide accumulation. We sought to investigate CF lung inflammation in the alveoli. METHODS: Lung tissue from 14 CF patients and four healthy individuals was analyzed for numbers of effector cells, elastin and collagen concentrations, inflammatory markers and density of Pseudomonas aeruginosa. Additionally, desmosine and isodesmosine concentrations were determined in 52 urine specimens from CF patients to estimate the burden of elastase activities in respiratory secretions. RESULTS: Elastin concentration was significantly decreased and collagen significantly increased in CF alveolar tissues as compared to age-matched, healthy individuals. Elastin split products were significantly increased in urine samples from patients with CF and correlated inversely with age, indicating local tissue remodelling due to elastin degradation by unopposed proteolytic enzymes. Alveolar inflammation was also characterized by a significant cell infiltration of neutrophils, macrophages and T cells, extensive nuclear factor-kappaB and insulin-like growth factor-1 activation in various cell types and increased intercellular adhesion molecule-1 expression, and increased numbers of myofibroblasts. Additionally, ceramide accumulated in type II alveolar epithelial cells, lacking CFTR. P. aeruginosa organisms were rarely present in inflamed alveoli. CONCLUSIONS: Chronic inflammation and remodeling is present in alveolar tissues of the CF lung and needs to be addressed by anti-inflammatory therapies.