Alterations in immune response and PPAR/LXR regulation in cystic fibrosis macrophages

BackgroundCystic fibrosis (CF) is characterized by an excessive inflammatory response in epithelial cells and macrophages. In CF mice, lung inflammation can be abrogated by oral treatment with docosahexaenoic acid (DHA). Since PPARs and LXRs are important regulators of inflammation and fatty acid metabolism in macrophages, we hypothesized that these pathways are dysregulated in CF macrophages and are corrected with DHA treatment.MethodsPeritoneal macrophages were obtained from wild type and cftr^−/− mice. LPS induced cytokine secretion and NFκB activity were analyzed with and without oral DHA treatment. The expression and activity of PPARα,γ, δ and LXRα were analyzed by RT-PCR and EMSA.ResultsLPS induced TNFα and IL-6 secretion and NFκB p65 activity were increased in CF macrophages. This was associated with low basal PPARγ expression and attenuated LPS induced induction of PPARδ, LXRα and ABCA1. DHA pretreatment in vivo decreased TNFα secretion and p65 activity, and increased PPARα and γ expression and function. The effects of DHA could be reproduced by PPAR agonists and blocked by a PPARα antagonist.ConclusionImpaired regulation of nuclear receptors may contribute to the abnormal LPS induced signaling in CF macrophages and is reversed by DHA.     

Defective regulation of epithelial Cl- permeability and protein secretion in cystic fibrosis: the putative basic defect

The search for a basic functional defect in CF appears to be converging on a defect in the regulation of epithelial Cl- permeability and perhaps protein secretion. Fundamental issues that remain unresolved include (1) the identity of the CF gene, (2) the precise role played by the CF gene product in regulating Cl- permeability and protein secretion, and (3) the identities and properties of alternate pathways for regulating Cl- permeability and protein secretion that are not compromised in CF. The first issue should be resolved in the near future as molecular genetic approaches are used to pinpoint the location of the CF locus on chromosome 7. The second issue is more complex and will require the development of generally useful assays of Cl- permeability and protein secretion that can be used to assess the abilities of candidate CF gene products to complement, or correct, the functional defect in CF cells. Characterizing the precise function of the CF gene product may be difficult if the regulatory pathways that control these cellular processes are complex (ie, involve multiple regulatory steps and second messengers) or if the CF gene is a regulatory gene (rather than a structural gene) that represses or induces the synthesis of proteins involved in modulating Cl- permeability and protein synthesis. The third issue relates to the development of therapeutic strategies for treating CF patients that involve elevating epithelial Cl- permeability or modulating protein secretion by pharmacologically activating regulatory pathways that are unaffected in CF. In this regard, it is important to note that the stimulation of the Cl- permeabilities of airway epithelial cells by Ca2+-mediated secretagogues appears not to be compromised in CF. Pharmacological manipulation of this or other regulatory pathways may provide a means to activate the Cl- permeabilities of CF affected cells.     

Bicarbonate in cystic fibrosis

Background

Cystic fibrosis (CF, mucoviscidosis) is caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), which is a chloride and bicarbonate channel necessary for fluid secretion and extracellular alkalization. For a long time, research concentrated on abnormal Cl^- and Na⁺ transport, but neglected bicarbonate as a crucial factor in CF.

Co-morbidity of cystic fibrosis and celiac disease in Scandinavian cystic fibrosis patients

BackgroundThe co-morbidity of cystic fibrosis (CF) and celiac disease (CD) has been reported sporadically since the 1960s. To our knowledge, this is the first time a systematic screening is performed in a large cohort of CF patients.MethodsTransglutaminase-IgA (TGA), endomysium-IgA (EMA) and total IgA in serum were measured in 790 CF patients (48% females, 86% with pancreatic insufficiency). Six patients were diagnosed with CD prior to the study, all receiving a gluten-free diet.Patients with elevated TGA (> 50 Units/mL) and a positive EMA test were offered a gastroscopy obtaining mucosal biopsies from the duodenum.ResultsFour new cases of CD were diagnosed. Two additional patients had positive serological tests, but normal biopsies.In total, 10 cases of CD (1.2%, 1:83) indicate a prevalence rate about three times higher than the general prevalence of CD in Norway and Sweden. No CD patients were detected in the Danish CF cohort.Patients diagnosed with untreated CD reported symptoms typical of both CF and CD (poor weight gain, loose and/or fatty stools, fatigue, irritability, abdominal pain). They improved after introduction of a gluten-free diet.ConclusionsSystematic screening for CD in a Scandinavian cohort of CF patients revealed a higher prevalence of CD than in the general population. Clinical signs of CD are difficult to differentiate from CF with malabsorption, and patients may go undiagnosed for a long time. In a population where CD is common we recommend screening for CD in patients with CF.     

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

BackgroundExposure 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.MethodsAfter 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.ResultsBoth 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.ConclusionIncreased PGE₂ in the CF airway suppresses phagocytosis of inhaled PM by AM.     

Non-tuberculous mycobacteria in cystic fibrosis

BACKGROUND—The clinical significance of thepresence of non-tuberculous mycobacteria in the sputum of patients withcystic fibrosis is unclear. A retrospective case-control study wasperformed to assess possible risk factors for non-tuberculousmycobacteria and its impact on clinical status in patients with cystic fibrosis.
METHODS—The records of all patients attending theLeeds cystic fibrosis clinics who were positive for non-tuberculousmycobacteria were examined. Each case was matched with two controls forsex, age, and respiratory function at the time of the firstnon-tuberculous mycobacteria isolate. Details of respiratory function,nutritional status, antibiotic and corticosteroid therapy,Shwachman-Kulczycki (S-K) score, Northern chest radiographic score, andthe frequency of isolation of other bacteria and fungi were collectedfrom two years before to two years after the first non-tuberculousmycobacteria isolate. The patients' genotype and the presence ofdiabetes mellitus were also recorded.
RESULTS—Non-tuberculous mycobacteria were isolatedfrom 14 patients out of a cystic fibrosis population of 372 (prevalence = 3.8%). No significant effect of non-tuberculous mycobacteria wasseen on respiratory function, nutritional status, or S-K score. There was a significant association with the number of intravenous antibiotic courses received before the first isolate with cases receiving, onaverage, twice as many courses as controls (cases 6.64, controls 2.86, 95% CI for difference 1.7 to 5.9). No significant difference was seenbetween cases and controls for Northern scores, previous steroidtherapy, or the incidence of diabetes mellitus.
CONCLUSIONS—Non-tuberculous mycobacteria infectionin patients with cystic fibrosis is uncommon and its clinical impactappears to be minimal over a two year period. Frequent intravenousantibiotic usage is a possible risk factor for colonisation withnon-tuberculous mycobacteria.

     

Musculoskeletal manifestations in cystic fibrosis

Although bone and joint manifestations are common in children with cystic fibrosis (CF), they have received little attention in adults. As compared to healthy individuals, bone mineral density is low, even with calcium intakes greater than 1500 mg/d. Nevertheless, calcium and phosphate levels in blood and urine are often normal, and vitamin D levels vary. Short stature with a low body mass index and central hypogonadism are the rule in these patients. Fractures and kyphosis are often reported. CF arthropathy occurs in 2-8.5% of patients. Arthritis develops, and there may be skin eruptions. Non-steroidal antiinflammatory drug therapy is effective. Hypertrophic osteoarthropathy associated with respiratory failure is present in 2-7% of patients. Rheumatoid arthritis, spondyloarthropathies, sarcoidosis, and amyloidosis have been reported in association with CF. Knee pain due to patellofemoral syndrome, quinolone-induced arthropathy, and mechanical back pain have been described. Rheumatoid factor titers are higher than in healthy controls, particularly in patients with episodic arthritis. No data are available on antiperinuclear factor or antikeratin antibody titers. Tests for antinuclear antibody are usually negative. Circulating immune complex levels and antibodies to heat shock proteins may be elevated. Antineutrophil cytoplasmic antibody of the bactericidal/permeability-increasing protein (BPI) or azurocidin (AZ) type has been reported, often in high titers (up to 40%).     

IgA nephropathy in cystic fibrosis

The kidney does not usually present specific lesions in cystic fibrosis (CF), although in recent years renal involvement has been reported, particularly amyloidosis and immune complex glomerulonephritis. IgA nephropathy is rare. We report four cases of IgA nephropathy out of five renal biopsies performed in the last three years in patients with CF and renal involvement and discuss the possibility of a relationship between IgA nephropathy and CF.     

Neutrophil dysfunction in cystic fibrosis

BackgroundExcessive neutrophil inflammation is the hallmark of cystic fibrosis (CF) airway disease. Novel technologies for characterizing neutrophil dysfunction may provide insight into the nature of these abnormalities, revealing a greater mechanistic understanding and new avenues for CF therapies that target these mechanisms.MethodsBlood was collected from individuals with CF in the outpatient clinic, CF individuals hospitalized for a pulmonary exacerbation, and non-CF controls. Using microfluidic assays and advanced imaging technologies, we characterized 1) spontaneous neutrophil migration using microfluidic motility mazes, 2) neutrophil migration to and phagocytosis of Staphylococcal aureus particles in a microfluidic arena, 3) neutrophil swarming on Candida albicans clusters, and 4) Pseudomonas aeruginosa-induced neutrophil transepithelial migration using micro-optical coherence technology (µOCT).ResultsParticipants included 44 individuals: 16 Outpatient CF, 13 Hospitalized CF, and 15 Non-CF individuals. While no differences were seen with spontaneous migration, CF neutrophils migrated towards S. aureus particles more quickly than non-CF neutrophils (p < 0.05). CF neutrophils, especially Hospitalized CF neutrophils, generated significantly larger aggregates around S. aureus particles over time. Hospitalized CF neutrophils were more likely to have dysfunctional swarming (p < 0.01) and less efficient clearing of C. albicans (p < 0.0001). When comparing trans-epithelial migration towards Pseudomonas aeruginosa epithelial infection, Outpatient CF neutrophils displayed an increase in the magnitude of transmigration and adherence to the epithelium (p < 0.05).ConclusionsAdvanced technologies for characterizing CF neutrophil function reveal significantly altered migratory responses, cell-to-cell clustering, and microbe containment. Future investigations will probe mechanistic basis for abnormal responses in CF to identify potential avenues for novel anti-inflammatory therapeutics.     

Appendico-ileal fistula in cystic fibrosis

This report describes a young woman with cystic fibrosis presenting with small bowel obstruction. Intraoperatively, an appendix with a wide lumen was found with a fistula to the distal ileum.     

Alveolar inflammation in cystic fibrosis

BackgroundIn 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.MethodsLung 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.ResultsElastin 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-κB 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.ConclusionsChronic inflammation and remodeling is present in alveolar tissues of the CF lung and needs to be addressed by anti-inflammatory therapies.     

Pulmonary nocardiosis in cystic fibrosis

BackgroundThe treatment of Nocardia species found in the sputum of cystic fibrosis patients is of unknown value.MethodsWe conducted a retrospective analysis of the impact of directed oral antibiotic therapy against Nocardia spp. isolated from the sputum of 17 cystic fibrosis patients over a 10-year period. Pulmonary Function Tests were used as the clinical indicator of the disease state and the data were analyzed by general linear mixed model statistics with univariate analysis.ResultsPulmonary Function Test values of all patients studied showed no significant difference before, during, or after the antibiotic treatment period. Treatment groups did not differ from non-treatment groups. This held true for Forced Expiratory Volume over 1 s and Functional Vital Capacity analysis. In addition, individual patient analysis did not reveal any trends or outliers.ConclusionsOral antibiotic therapy of cystic fibrosis patients colonized with Nocardia does not appear to affect clinical outcome. This suggests that deferring therapy may be an acceptable alternative and justifies conducting a future placebo controlled trial. In addition, this study model may be useful in analyzing the effect of therapy on other rare and difficult organisms, such as fungi and mycobacteria in the cystic fibrosis population.