Ute Graepler-Mainka

Flagellin Induces Myeloid-Derived Suppressor Cells: Implications for Pseudomonas aeruginosa Infection in Cystic Fibrosis Lung Disease

Pseudomonas aeruginosa persists in patients with cystic fibrosis (CF) and drives CF lung disease progression. P. aeruginosa potently activates the innate immune system, mainly mediated through pathogen-associated molecular patterns, such as flagellin. However, the host is unable to eradicate this flagellated bacterium efficiently. The underlying immunological mechanisms are incompletely understood. Myeloid-derived suppressor cells (MDSCs) are innate immune cells generated in cancer and proinflammatory microenvironments and are capable of suppressing T cell responses. We hypothesized that P. aeruginosa induces MDSCs to escape T cell immunity. In this article, we demonstrate that granulocytic MDSCs accumulate in CF patients chronically infected with P. aeruginosa and correlate with CF lung disease activity. Flagellated P. aeruginosa culture supernatants induced the generation of MDSCs, an effect that was 1) dose-dependently mimicked by purified flagellin protein, 2) significantly reduced using flagellin-deficient P. aeruginosa bacteria, and 3) corresponded to TLR5 expression on MDSCs in vitro and in vivo. Both purified flagellin and flagellated P. aeruginosa induced an MDSC phenotype distinct from that of the previously described MDSC-inducing cytokine GM-CSF, characterized by an upregulation of the chemokine receptor CXCR4 on the surface of MDSCs. Functionally, P. aeruginosa–infected CF patient ex vivo–isolated as well as flagellin or P. aeruginosa in vitro–generated MDSCs efficiently suppressed polyclonal T cell proliferation in a dose-dependent manner and modulated Th17 responses. These studies demonstrate that flagellin induces the generation of MDSCs and suggest that P. aeruginosa uses this mechanism to undermine T cell–mediated host defense in CF and other P. aeruginosa–associated chronic lung diseases.

Therapy of CF-Patients with Amitriptyline and Placebo - a Randomised, Double-Blind, Placebo-Controlled Phase IIb Multicenter, Cohort-Study

Background/Aims: Several recent studies revealed an accumulation of ceramide in bronchial, tracheal and intestinal epithelial cells of mice and patients with cystic fibrosis (CF). Normalization of ceramide concentrations in lungs of CF mice employing the functional acid sphingomyelinase inhibitor amitriptyline also normalized mucociliary clearance, chronic inflammation and infection susceptibility to pulmonary P. aeruginosa in these mice. Methods: To test for a beneficial effect of amitriptyline in vivo, we performed a phase IIb randomised, double-blind, placebo-controlled study. Twenty-one CF patients were treated with 25 mg/d amitriptyline twice daily for 28 days. The placebo consisted of 19 patients and was also treated twice per day. The primary endpoint was the change in lung function in the intention-to-treat (ITT) population. Secondary endpoints were ceramide levels in epithelial cells and safety. Results: After treatment, forced expiratory volume in 1 sec predicted (FEV1) increased 6.3±11.5% (p=0.08) in the ITT population (36 of 40 CF patients) and 8.5±10% (p=0.013) in the per protocol (PP) population (29 of 40 patients). Ceramide levels decreased in nasal epithelial cells after amitriptyline treatment. Amitriptyline had no severe and only mild and mostly transient adverse effects, i.e. xerostomia and tiredness. Conclusion: Amitriptyline is safe in CF-patients, increases FEV1 and reduces ceramide in lung cells of CF patients.

Regulatory T-cell impairment in cystic fibrosis patients with chronic pseudomonas infection.

RATIONALE Patients with cystic fibrosis (CF) lung disease have chronic airway inflammation driven by disrupted balance of T-cell (Th17 and Th2) responses. Regulatory T cells (Tregs) dampen T-cell activation, but their role in CF is incompletely understood. OBJECTIVES To characterize numbers, function, and clinical impact of Tregs in CF lung disease. METHODS Tregs were quantified in peripheral blood and airway samples from patients with CF and from lung disease control patients without CF and healthy control subjects. The role of Pseudomonas aeruginosa and CF transmembrane conductance regulator (CFTR) in Treg regulation was analyzed by using in vitro and murine in vivo models. MEASUREMENTS AND MAIN RESULTS Tregs were decreased in peripheral blood and airways of patients with CF compared with healthy controls or lung disease patients without CF and correlated positively with lung function parameters. Patients with CF with chronic P. aeruginosa infection had lower Tregs compared with patients with CF without P. aeruginosa infection. Genetic knockout, pharmacological inhibition, and P. aeruginosa infection studies showed that both P. aeruginosa and CFTR contributed to Treg dysregulation in CF. Functionally, Tregs from patients with CF or from Cftr(-/-) mice were impaired in suppressing conventional T cells, an effect that was enhanced by P. aeruginosa infection. The loss of Tregs in CF affected memory, but not naive Tregs, and manifested gradually with disease progression. CONCLUSIONS Patients with CF who have chronic P. aeruginosa infection show an age-dependent, quantitative, and qualitative impairment of Tregs. Modulation of Tregs represents a novel strategy to rebalance T-cell responses, dampen inflammation, and ultimately improve outcomes for patients with infective CF lung disease.

Microbial colonization and lung function in adolescents with cystic fibrosis

With intensified antibiotic therapy and longer survival, patients with cystic fibrosis (CF) are colonized with a more complex pattern of bacteria and fungi. However, the clinical relevance of these emerging pathogens for lung function remains poorly defined. The aim of this study was to assess the association of bacterial and fungal colonization patterns with lung function in adolescent patients with CF. Microbial colonization patterns and lung function parameters were assessed in 770 adolescent European (German/Austrian) CF patients in a retrospective study (median follow-up time: 10years). Colonization with Pseudomonas aeruginosa and MRSA were most strongly associated with loss of lung function, while mainly colonization with Haemophilus influenzae was associated with preserved lung function. Aspergillus fumigatus was the only species that was associated with an increased risk for infection with P. aeruginosa. Microbial interaction analysis revealed three distinct microbial clusters within the longitudinal course of CF lung disease. Collectively, this study identified potentially protective and harmful microbial colonization patterns in adolescent CF patients. Further studies in different patient cohorts are required to evaluate these microbial patterns and to assess their clinical relevance.

Factors Associated with Worse Lung Function in Cystic Fibrosis Patients with Persistent Staphylococcus aureus.

Background Staphylococcus aureus is an important pathogen in cystic fibrosis (CF). However, it is not clear which factors are associated with worse lung function in patients with persistent S. aureus airway cultures. Our main hypothesis was that patients with high S. aureus density in their respiratory specimens would more likely experience worsening of their lung disease than patients with low bacterial loads. Methods Therefore, we conducted an observational prospective longitudinal multi-center study and assessed the association between lung function and S. aureus bacterial density in respiratory samples, co-infection with other CF-pathogens, nasal S. aureus carriage, clinical status, antibiotic therapy, IL-6- and IgG-levels against S. aureus virulence factors. Results 195 patients from 17 centers were followed; each patient had an average of 7 visits. Data were analyzed using descriptive statistics and generalized linear mixed models. Our main hypothesis was only supported for patients providing throat specimens indicating that patients with higher density experienced a steeper lung function decline (p<0.001). Patients with exacerbations (n = 60), S. aureus small-colony variants (SCVs, n = 84) and co-infection with Stenotrophomonas maltophilia (n = 44) had worse lung function (p = 0.0068; p = 0.0011; p = 0.0103). Patients with SCVs were older (p = 0.0066) and more often treated with trimethoprim/sulfamethoxazole (p = 0.0078). IL-6 levels positively correlated with decreased lung function (p<0.001), S. aureus density in sputa (p = 0.0016), SCVs (p = 0.0209), exacerbations (p = 0.0041) and co-infections with S. maltophilia (p = 0.0195) or A. fumigatus (p = 0.0496). Conclusions In CF-patients with chronic S. aureus cultures, independent risk factors for worse lung function are high bacterial density in throat cultures, exacerbations, elevated IL-6 levels, presence of S. aureus SCVs and co-infection with S. maltophilia. Trial Registration ClinicalTrials.gov NCT00669760

Expression and Regulation of Interferon-Related Development Regulator–1 in Cystic Fibrosis Neutrophils

A genome-wide association study identified interferon-related development regulator-1 (IFRD1), a protein expressed by neutrophils, as a key modifier gene in cystic fibrosis (CF) lung disease. Here, we investigated the expression and regulation of IFRD1 in CF neutrophils. IFRD1 expression was quantified in peripheral blood and airway neutrophils from patients with CF, patients with non-CF lung disease, and healthy control subjects. The regulation of IFRD1 expression was analyzed using isolated neutrophils and ex vivo stimulation assays with CF airway fluids. IFRD1 single-nucleotide polymorphisms (SNPs) were analyzed in a CF cohort (n = 572) and correlated with longitudinal lung function and IFRD1 expression. Patients with CF expressed higher protein levels of IFRD1 in peripheral blood neutrophils compared with healthy or non-CF disease control subjects. Within patients with CF, IFRD1 protein expression levels in neutrophils were lower in airway fluids compared with peripheral blood. High IFRD1 expression was positively associated with the production of reactive oxygen species (ROS) in CF neutrophils. In vitro regulation studies showed that CF airway fluid and the CF-characteristic chemokines CXCL8 and CXCL2 down-regulated IFRD1 expression in neutrophils, an effect that was mediated through CXCR2. Genetic analyses showed that three IFRD1 SNPs were associated with longitudinal declines in lung function, and modulated IFRD1 expression. These studies demonstrate that IFRD1 expression is systemically up-regulated in human CF neutrophils, is linked to the production of ROS, and is modulated by chemokines in CF airway fluids, depending on the IFRD1 genotype. Understanding the regulation of IFRD1 may pave the way for novel therapeutic approaches to target neutrophilic inflammation in CF.

Chitinase activation in patients with fungus-associated cystic fibrosis lung disease

BACKGROUND Chitinases have recently gained attention in the field of pulmonary diseases, particularly in asthma and chronic obstructive pulmonary disease, but their potential role in patients with cystic fibrosis (CF)-associated lung disease remains unclear. OBJECTIVE The aim of this study was to assess chitinase activity systemically and in the airways of patients with CF and asthma compared with healthy subjects. Additionally, we assessed factors that regulate chitinase activity within the lungs of patients with CF. METHODS Chitinase activities were quantified in serum and bronchoalveolar lavage fluid from patients with CF, asthmatic patients, and healthy control subjects. Mechanistically, the role of CF airway proteases and genetic chitinase deficiency was assessed. RESULTS Chitinase activity was systemically increased in patients with CF compared with that in healthy control subjects and asthmatic patients. Further stratification showed that chitinase activity was enhanced in patients with CF colonized with Candida albicans compared with that in noncolonized patients. CF proteases degraded chitinases in the airway microenvironment of patients with CF. Genetic chitinase deficiency was associated with C albicans colonization in patients with CF. CONCLUSION Patients with CF have enhanced chitinase activation associated with C albicans colonization. Therefore chitinases might represent a novel biomarker and therapeutic target for CF-associated fungal disease.

Long-Term Pulmonal Therapy of Cystic Fibrosis-Patients with Amitriptyline

Background/Aims: Several recent clinical studies revealed an accumulation of ceramide in bronchial epithelial cells of patients with cystic fibrosis (CF). Degradation of ceramide concentrations in lungs of CF patients employing the functional acid sphingomyelinase inhibitor amitriptyline revealed a benefit in lung function, weight and exacerbation rates. Methods: To test for a beneficial effect of amitriptyline in vivo, we performed two phase II randomised, double-blind, placebo-controlled studies. CF patients were treated with 25 mg amitriptyline twice daily, i.e. a total dose of 50 mg/d. After those two studies part of the patients used amitriptyline in an off-lable-use for routine treatment. These patients were observed after one, two and three years after continuous use of amitriptyline and were matched with those patients who were not treated. These patients were used as a control group. Results: After one year of treatment, forced expiratory volume in 1 sec predicted (FEV1) increased significantly by 7.6±7.0%, p=<0.001, and weight increased by 2.1±2.3kg, p=<0.001 in the amitriptyline population (n=20), whereas FEV1 decreased significantly in the control group by 1.8±3.3%, p=0.010, and weight increased by 1.1±2.7kg, p=0.010 (n=14). After two years of treatment, FEV1 increased significantly by 5.6±10.3%, p=0.009, and weight increased by 3.6±2.9kg, p=<0.001 in the amitriptyline population (n=12). In contrast, FEV1 decreased in the control group by 2.1±3.7%, p=0.051 and weight increased by only 0.4±2.9kg, p=0.31 (n=10). After three years of treatment, FEV1 increased significantly by 7.7±8%, p=0.050, and weight increased by 7.3±3.8kg, p=0.016, in the amitriptyline population (n=5), whereas FEV1 decreased in the control group by 1.0±1.3%, p=0.075 and weight increased by 0.4±1.5kg, p=0.29 (n=5). Conclusion: Amitriptyline significantly increases FEV1, reduces ceramide in lung cells and increases weight of CF patients.

157 Long-term impact of fungi on pediatric cystic fibrosis lung disease

Background and Objectives: Fungi, particularly Aspergillus and Candida species, are increasingly found in cystic fibrosis (CF) airway fluids. However, their association with other CF pathogens, medications and lung function, especially in CF children, remains elusive. We analyzed the relationship of fungal colonization to microbiological and clinical parameters of pediatric CF patients. Methods and Results: Fungal colonization and long-term clinical parameters like BMI and lung function were retrospectively studied in over 500 CF patients. Colonization was defined based on Chotirmall et al. (Chest 2010). Candida albicans (CA) was the most prevalent fungus detected in CF airway fluids, followed by C. non-albicans > Aspergillus fumigatus (AF) > A. non-fumigatus species. We found an association between fungal colonization and (among other parameters) bacterial co-colonization, lung function, BMI and antibiotic therapy. Conclusion: This study suggests that colonization with CA or AF is affected by bacterial co-colonization and may modulate the disease severity already in pediatric CF patients.

WS19.5 Characterization of fungal colonization phenotypes in pediatric cystic fibrosis lung disease

Objectives: Fungi, particularly Aspergillus and Candida species, are increasingly found in cystic fibrosis (CF) airway fluids. However, their relationship to other CF pathogens, medications and lung function, especially in CF children, remains poorly understood. To address this question, we analyzed the associations of fungal colonization with microbiological and clinical parameters of pediatric CF patients. Methods: Fungal colonization was categorized in n = 128 CF patients based on Chotirmall et al. (Chest 2010). Candida albicans (CA) was the most prevalent fungus detected in CF airway fluids, followed by C. non-albicans > Aspergillus fumigatus (AF) > A. non-fumigatus species. Colonization with CA correlated positively with age, inhaled antibiotic use, and Aspergillus species, while an inverse correlation with Haemophilus and no association with S. aureus or Pseudomonas was found. Colonization with AF correlated positively with age, inhaled antibiotics, Pseudomonas, Stenotrophomonas, atypical mycobacteria and CF-related diabetes and inversely with Haemophilus. ABPA showed no correlation with AF colonization, but with non-fumigatus species and use of azithromycin. Colonization with AF or CA correlated inversely with cross-sectional FEV1, but not with MEF25. Colonization with AF correlated with longitudinal FEV1 decline. Conclusion: This study suggests that colonization with CA or AF is affected by bacterial co-colonization and may modulate lung function already in pediatric CF.