Peter Greally

LL-37 complexation with glycosaminoglycans in cystic fibrosis lungs inhibits antimicrobial activity, which can be restored by hypertonic saline.

There is an abundance of antimicrobial peptides in cystic fibrosis (CF) lungs. Despite this, individuals with CF are susceptible to microbial colonization and infection. In this study, we investigated the antimicrobial response within the CF lung, focusing on the human cathelicidin LL-37. We demonstrate the presence of the LL-37 precursor, human cathelicidin precursor protein designated 18-kDa cationic antimicrobial protein, in the CF lung along with evidence that it is processed to active LL-37 by proteinase-3. We demonstrate that despite supranormal levels of LL-37, the lung fluid from CF patients exhibits no demonstrable antimicrobial activity. Furthermore Pseudomonas killing by physiological concentrations of exogenous LL-37 is inhibited by CF bronchoalveolar lavage (BAL) fluid due to proteolytic degradation of LL-37 by neutrophil elastase and cathepsin D. The endogenous LL-37 in CF BAL fluid is protected from this proteolysis by interactions with glycosaminoglycans, but while this protects LL-37 from proteolysis it results in inactivation of LL-37 antimicrobial activity. By digesting glycosaminoglycans in CF BAL fluid, endogenous LL-37 is liberated and the antimicrobial properties of CF BAL fluid restored. High sodium concentrations also liberate LL-37 in CF BAL fluid in vitro. This is also seen in vivo in CF sputum where LL-37 is complexed to glycosaminoglycans but is liberated following nebulized hypertonic saline resulting in increased antimicrobial effect. These data suggest glycosaminoglycan–LL-37 complexes to be potential therapeutic targets. Factors that disrupt glycosaminoglycan–LL-37 aggregates promote the antimicrobial effects of LL-37 with the caveat that concomitant administration of antiproteases may be needed to protect the now liberated LL-37 from proteolytic cleavage.

Sputum tumour necrosis factor-alpha and leukotriene concentrations in cystic fibrosis.

It is postulated that a vigorous host inflammatory response in the cystic fibrosis lung contributes to lung injury. Tumour necrosis factor-alpha (TNF-alpha) may play a part in that process and in the generation of leukotrienes. Therefore, the relationships between sputum TNF-alpha, leukotriene concentration, and lung function abnormalities in 16 children with cystic fibrosis were investigated. Each subject provided sputum samples and performed spirometry. TNF-alpha was measured by enzyme linked immunosorbent assay; individual leukotrienes were separated using high performance liquid chromatography and quantified by radioimmunoassay. The geometric mean concentration of TNF-alpha was 129.7 pg/ml and 95% confidence interval 48.2 to 348.3. Mean (SEM) leukotriene B4 (LTB4) was 97.8 (22.9) pmol/g and total cysteinyl leukotrienes were 60.9 (14.8) pmol/g. Mean (SD) forced expiratory volume in one second (FEV1) of the group was 53 (15)% of predicted and forced vital capacity (FVC) was 65 (14)% of predicted. There was a significant positive correlation between TNF-alpha and both LTB4 and the total cysteinyl leukotriene sputum content. An inverse relationship existed between TNF-alpha and FEV1 and FVC. Moreover, a negative correlation was observed between sputum LTB4 and FEV1 and FVC. These results suggest that TNF-alpha and the leukotrienes may participate in the airways inflammation and airflow obstruction observed in cystic fibrosis subjects and support the hypothesis that TNF-alpha upregulates the 5-lipoxygenase pathway in vivo.

Nebulized Hypertonic Saline Decreases IL-8 in Sputum of Patients with Cystic Fibrosis

RATIONALE Inflammation within the cystic fibrosis (CF) lung is mediated by inflammatory chemokines, such as IL-8. IL-8 is protected from proteolytic degradation in the airways by binding to glycosaminoglycans, while remaining active. Evidence that increased hypertonicity of airway secretions induced by hypertonic saline treatment alters levels of IL-8 is lacking. OBJECTIVES To investigate the antiinflammatory effect of hypertonic saline (HTS) treatment within the CF lung by focusing on IL-8. METHODS Degradation of IL-8 in CF lung secretions after treatment with glycosaminoglycan lyases and HTS was analyzed by Western blot analysis and ELISA. The ex vivo chemotactic activity of purified neutrophils in response to CF airway secretions was evaluated post nebulization of HTS (7% saline). MEASUREMENTS AND MAIN RESULTS In vivo CF bronchoalveolar lavage fluid (BALF) IL-8 levels were significantly higher than the control group (P < 0.05). Digesting glycosaminoglycans in CF BALF displaced IL-8 from glycosaminoglycan matrices, rendering the chemokine susceptible to proteolytic cleavage. High sodium concentrations also liberate IL-8 in CF BALF in vitro, and in vivo in CF sputum from patients receiving aerosolized HTS, resulting in degradation of IL-8 and decreased neutrophil chemotactic efficiency. CONCLUSIONS Glycosaminoglycans possess the ability to influence the chemokine profile of the CF lung by binding and stabilizing IL-8, which promotes neutrophil chemotaxis and activation. Nebulized hypertonic saline treatment disrupts the interaction between glycosaminoglycans and IL-8, rendering IL-8 susceptible to proteolytic degradation with subsequent decrease in neutrophil chemotaxis, thereby facilitating resolution of inflammation.

Interleukin-1 alpha, soluble interleukin-2 receptor, and IgG concentrations in cystic fibrosis treated with prednisolone.

The cytokines interleukin-1 and interleukin-2 participate in the inflammatory response, and may contribute to hypergammaglobulinaemia G and the development of lung injury in cystic fibrosis. Anti-inflammatory treatment with corticosteroids may attenuate this response. The effect of a 12 week course of oral prednisolone on spirometry and serum concentrations of interleukin-1 alpha (IL-1 alpha), soluble interleukin-2 receptor (sIL-2R), and IgG was investigated in 24 children with cystic fibrosis. Prednisolone was administered, in a double blind and placebo controlled manner, at an initial dose of 2 mg/kg daily for 14 days and tapered to 1 mg/kg on alternate days for 10 weeks. The treated group (n = 12) experienced an increase in forced expiratory volume in one second and forced vital capacity at 14 days, however, these changes were smaller at 12 weeks. In the treated group, change in pulmonary function was associated with decreased serum IgG and cytokine concentrations. Prednisolone suppresses serum concentrations of these cytokines, which may participate in the inflammatory response, the excessive synthesis of IgG, and airflow obstruction observed in cystic fibrosis patients.

VALIDATION OF CONTINUOUS GLUCOSE MONITORING IN CHILDREN AND ADOLESCENTS WITH CYSTIC FIBROSIS - A PROSPECTIVE COHORT STUDY

OBJECTIVE To validate continuous glucose monitoring (CGM) in children and adolescents with cystic fibrosis. RESEARCH DESIGN AND METHODS Paired oral glucose tolerance tests (OGTTs) and CGM monitoring was undertaken in 102 children and adolescents with cystic fibrosis (age 9.5–19.0 years) at baseline (CGM1) and after 12 months (CGM2). CGM validity was assessed by reliability, reproducibility, and repeatability. RESULTS CGM was reliable with a Bland-Altman agreement between CGM and OGTT of 0.81 mmol/l (95% CI for bias ± 2.90 mmol/l) and good correlation between the two (r = 0.74–0.9; P < 0.01). CGM was reproducible with no significant differences in the coefficient of variation of the CGM assessment between visits and repeatable with a mean difference between CGM1 and CGM2 of 0.09 mmol/l (95% CI for difference ± 0.46 mmol/l) and a discriminant ratio of 13.0 and 15.1, respectively. CONCLUSIONS In this cohort of children and adolescents with cystic fibrosis, CGM performed on two occasions over a 12-month period was reliable, reproducible, and repeatable.

Peripheral muscle strength in young males with cystic fibrosis

BACKGROUND In children with cystic fibrosis there is a decrease in peak work capacity and oxygen consumption on maximal exercise testing when compared to controls. Previous studies have shown that peripheral muscle force is decreased in children with cystic fibrosis even in those with minimal changes in lung function. However, no studies have examined peripheral muscle strength using isokinetic dynamometry which permits measurement of muscle strength throughout range and is considered the gold standard in orthopaedics and sports medicine. METHODS Isokinetic muscle strength was measured in the knee flexors and extensors and shoulder flexors and extensors at two speeds of movement in children with cystic fibrosis and matched controls. Activity levels in both groups were calculated. RESULTS Thirteen subjects and 13 age and height matched controls were assessed. Average peak torque was calculated and expressed in terms of body weight. There was a significant difference in peak torque/body weight in children with cystic fibrosis when compared to controls. FEV1 was significantly correlated with knee muscle strength and shoulder flexion at 90 degrees /s in subjects with CF. CONCLUSION Children with CF had lower muscle strength than control subjects. Airflow limitation was associated with decreased muscle strength. The relationship between muscle strength and exercise tolerance requires investigation.

Outcome in Cystic Fibrosis Liver Disease

OBJECTIVES:Evidence suggests that cystic fibrosis liver disease (CFLD) does not affect mortality or morbidity in patients with cystic fibrosis (CF). The importance of gender and age in outcome in CF makes selection of an appropriate comparison group central to the interpretation of any differences in mortality and morbidity in patients with CFLD.METHODS:This is a 7-year follow-up of 42 children with CFLD and their age- and sex-matched controls. Participants were reviewed clinically, biochemically, and radiologically at follow-up.RESULTS:Overall, 85% (72 of 84) of the original cohort were included, 36 CFLD participants and 36 CF controls. There was no significant difference in the number of deaths/transplants between groups (7 of 36 (19.4%) CFLD participants, 3 of 36 (8.3%) CF controls). There was a tendency for participants with CFLD to die younger than their respective CF controls. There was no difference in height, weight, body mass index, or pulmonary function between the groups. Nutritional parameters (sum skinfold thickness 31.6 vs. 42.3, P=0.03; mean upper arm fat area 15.08 vs. 10.59, P=0.001; Shwachman score 43.7 vs. 32.1, P=0.001) were worse among CFLD participants than among CF controls. Cystic fibrosis-related diabetes was more common in CFLD participants (11 of 27 (40.7%) vs. 5 of 33 (15.2%), P=0.02). Eight children (22.2%) with evidence of CFLD at baseline had no clinical evidence of liver disease as adults.CONCLUSIONS:Patients with CFLD have a more severe CF phenotype than do CF patients without liver disease. However, a subgroup of children with CFLD will not manifest clinically significant liver disease as adults.

Vitamin D receptor agonists inhibit pro-inflammatory cytokine production from the respiratory epithelium in cystic fibrosis ☆

BACKGROUND 1,25-Dihydroxycholecalciferol (1,25(OH)(2)D(3)) has been shown to mitigate epithelial inflammatory responses after antigen exposure. Patients with cystic fibrosis (CF) are at particular risk for vitamin D deficiency. This may contribute to the exaggerated inflammatory response to pulmonary infection in CF. METHODS CF respiratory epithelial cell lines were exposed to Pseudomonas aeruginosa lipopolysaccharide (LPS) and Pseudomonas conditioned medium (PCM) in the presence or absence of 1,25(OH)(2)D(3) or a range of vitamin D receptor (VDR) agonists. Levels of IL-6 and IL-8 were measured in cell supernatants, and cellular total and phosphorylated IκBα were determined. Levels of human cathelicidin antimicrobial peptide (hCAP18) mRNA and protein were measured in cells after treatment with 1,25(OH)(2)D(3). RESULTS Pretreatment with 1,25(OH)(2)D(3) was associated with significant reductions in IL-6 and IL-8 protein secretion after antigen exposure, a finding reproduced with a range of low calcaemic VDR agonists. 1,25(OH)(2)D(3) treatment led to a decrease in IκBα phosphorylation and increased total cellular IκBα. Treatment with 1,25(OH)(2)D(3) was associated with an increase in hCAP18/LL-37 mRNA and protein levels. CONCLUSIONS Both 1,25(OH)(2)D(3) and other VDR agonists significantly reduce the pro-inflammatory response to antigen challenge in CF airway epithelial cells. VDR agonists have significant therapeutic potential in CF.

Gaviscon and Carobel compared with cisapride in gastro-oesophageal reflux.

We compared the efficacy of the prokinetic agent cisapride with that of Gaviscon (an alginate/alkaline compound) plus Carobel (carob seed flour) in the treatment of gastrooesophageal reflux (GOR). Fifty infants with confirmed GOR received either oral cisapride (0.8 mg/kg/day) or Gaviscon plus Carobel for one month in a randomised, parallel group study. Parental evaluations, diary scores, and 24 hour lower oesophageal pH recordings before and at the end of each treatment were compared. In the cisapride group 14/26 (53%) were considered better by their parents compared with 19/24 (79%) of those who received Gaviscon plus Carobel. Diary scores, range (0.00-1.00), improved in both groups with the median change being greater in the Gaviscon plus Carobel group (-0.21) than the cisapride group (-0.15). Five of 17 pH variables had significantly improved from baseline in infants who had received cisapride compared with 11/17 in those receiving Gaviscon plus Carobel. However, unpaired analysis of diary and pH data showed no significant differences between the two groups. We conclude that first line treatment of GOR with cisapride is no more effective than conventional treatment with Gaviscon plus Carobel.

IL-8 Dictates Glycosaminoglycan Binding and Stability of IL-18 in Cystic Fibrosis

Dysregulation of airway inflammation contributes to lung disease in cystic fibrosis (CF). Inflammation is mediated by inflammatory cytokines, including IL-8, which illustrates an increase in biological half-life and proinflammatory activity when bound to glycosaminoglycans (GAGs). The aim of this project was to compare IL-8 and IL-18 for their relative stability, activity, and interaction with GAGs, including chondroitin sulfate, hyaluronic acid, and heparan sulfate, present in high quantities in the lungs of patients with CF. Bronchoalveolar lavage fluid was collected from patients with CF (n = 28), non-CF controls (n = 14), and patients with chronic obstructive pulmonary disease (n = 12). Increased levels of IL-8 and reduced concentrations of IL-18 were detected in bronchial samples obtained from CF individuals. The low level of IL-18 was not a defect in IL-18 production, as the pro- and mature forms of the molecule were expressed and produced by CF epithelial cells and monocytes. There was, however, a marked competition between IL-8 and IL-18 for binding to GAGs. A pronounced loss of IL-18 binding capacity occurred in the presence of IL-8, which displaced IL-18 from these anionic-matrices, rendering the cytokine susceptible to proteolytic degradation by neutrophil elastase. As a biological consequence of IL-18 degradation, reduced levels of IL-2 were secreted by Jurkat T lymphocytes. In conclusion, a novel mechanism has been identified highlighting the potential of IL-8 to determine the fate of other inflammatory molecules, such as IL-18, within the inflammatory milieu of the CF lung.