Pseudomonas aeruginosa Induced Airway Epithelial Injury Drives Fibroblast Activation: A Mechanism in Chronic Lung Allograft Dysfunction.

Bacterial infections after lung transplantation cause airway epithelial injury and are associated with an increased risk of developing bronchiolitis obliterans syndrome. The damaged epithelium is a source of alarmins that activate the innate immune system, yet their ability to activate fibroblasts in the development of bronchiolitis obliterans syndrome has not been evaluated. Two epithelial alarmins were measured longitudinally in bronchoalveolar lavages from lung transplant recipients who developed bronchiolitis obliterans syndrome and were compared to stable controls. In addition, conditioned media from human airway epithelial cells infected with Pseudomonas aeruginosa was applied to lung fibroblasts and inflammatory responses were determined. Interleukin-1 alpha (IL-1α) was increased in bronchoalveolar lavage of lung transplant recipients growing P. aeruginosa (11.5 [5.4-21.8] vs. 2.8 [0.9-9.4] pg/mL, p < 0.01) and was significantly elevated within 3 months of developing bronchiolitis obliterans syndrome (8.3 [1.4-25.1] vs. 3.6 [0.6-17.1] pg/mL, p < 0.01), whereas high mobility group protein B1 remained unchanged. IL-1α positively correlated with elevated bronchoalveolar lavage IL-8 levels (r(2)  = 0.6095, p < 0.0001) and neutrophil percentage (r(2)  = 0.25, p = 0.01). Conditioned media from P. aeruginosa infected epithelial cells induced a potent pro-inflammatory phenotype in fibroblasts via an IL-1α/IL-1R-dependent signaling pathway. In conclusion, we propose that IL-1α may be a novel therapeutic target to limit Pseudomonas associated allograft injury after lung transplantation.

Lack of association between KIR and HLA-C type and susceptibility to idiopathic bronchiectasis.

INTRODUCTION: Idiopathic bronchiectasis is a poorly defined disease characterised by persistent inflammation, infection and progressive lung damage. Natural killer (NK) cells provide a major defense against infection, through the interaction of their surface receptors, including the activating and inhibitory killer immunoglobulin-like receptors (KIR), and human leukocyte antigens (HLA) class I molecules. Homozygosity for HLA-C has been shown in a single study to confer increased genetic susceptibility to idiopathic bronchiectasis. We aimed to assess whether the KIR and HLA repertoire, alone or in combination, may influence the risk of developing idiopathic bronchiectasis, in an independent replication study. METHODS: In this prospective, observational, case-control association study, 79 idiopathic bronchiectasis patients diagnosed following extensive aetiological investigation were compared with 98 anonymous, healthy, age, sex and ethnically-matched controls attending blood donor sessions in the same geographical location. DNA extraction was performed according to standardised techniques. Determination of presence or absence of KIR genes was performed by a sequence specific oligonucleotide probe method. Allele frequencies for the proposed KIR, HLA-B and HLA-C risk alleles both individually and in combinations were compared. RESULTS: We found no significant differences in allele frequency between the idiopathic bronchiectasis and control samples, whether considering HLA-C group homozygosity alone or in combination with the KIR type. DISCUSSION: Our results do not show an association between HLA-C and KIR and therefore do not confirm previous positive findings. This may be explained by the lower frequency of HLA-C1 group homozygosity in the control population of the previous study (27.2%), compared to 42.3% in our study, which is consistent with the genetic profiling of control groups across the UK. The previous positive association study may therefore have been driven by an anomalous control group. Further larger prospective multicentre replication studies are needed to determine if an association exists.

IL-1α released from damaged epithelial cells is sufficient and essential to trigger inflammatory responses in human lung fibroblasts.

Activation of the innate immune system plays a key role in exacerbations of chronic lung disease, yet the potential role of lung fibroblasts in innate immunity and the identity of epithelial danger signals (alarmins) that may contribute to this process are unclear. The objective of the study was to identify lung epithelial-derived alarmins released during endoplasmic reticulum stress (ER stress) and oxidative stress and evaluate their potential to induce innate immune responses in lung fibroblasts. We found that treatment of primary human lung fibroblasts (PHLFs) with conditioned media from damaged lung epithelial cells significantly upregulated interleukin IL-6, IL-8, monocyte chemotactic protein-1, and granulocyte macrophage colony-stimulating factor expression (P<0.05). This effect was reduced with anti-IL-1α or IL-1Ra but not anti-IL-1ß antibody. Costimulation with a Toll-like receptor 3 ligand, polyinosinic-polycytidylic acid (poly I:C), significantly accentuated the IL-1α-induced inflammatory phenotype in PHLFs, and this effect was blocked with inhibitor of nuclear factor kappa-B kinase subunit beta and TGFß-activated kinase-1 inhibitors. Finally, Il1r1-/- and Il1a-/- mice exhibit reduced bronchoalveolar lavage (BAL) neutrophilia and collagen deposition in response to bleomycin treatment. We conclude that IL-1α plays a pivotal role in triggering proinflammatory responses in fibroblasts and this process is accentuated in the presence of double-stranded RNA. This mechanism may be important in the repeated cycles of injury and exacerbation in chronic lung disease.

Phenotyping adults with non-cystic fibrosis bronchiectasis: a prospective observational cohort study.

BACKGROUND: Bronchiectasis is the outcome of a number of different airway insults. Very few studies have characterised the aetiology and utility of a dedicated screening proforma in adult patients attending a general bronchiectasis clinic. METHODS: A prospective observational study of 189 bronchiectasis patients attending two centres in the North East of England over a two-year period was performed. RESULTS: The aetiology of bronchiectasis was identified in 107/189(57%) patients. Idiopathic bronchiectasis (IB) represented the largest subgroup (43%). Post-infection bronchiectasis (PIB) constituted the largest proportion (24%) of known causes. Mean age (SD) at diagnosis was 54(20) years with a mean age at symptom onset of 37(24) years, accounting for a diagnostic delay of 17 years. Age of symptom onset was significantly younger in patients with PIB compared to IB (p < 0.0001) and in Pseudomonas sputum positive patients (p = 0.007). Screening for APBA and total immunoglobulin deficiency identified 9 (5%) patients who then had tailored treatment. Routine screening for other aetiologies was deemed unnecessary. CONCLUSION: IB and PIB accounted for two thirds of cases of bronchiectasis in a general population. We recommend routine screening for ABPA and total immunoglobulin deficiency but not for other rarer aetiologies.

TNFα from classically activated macrophages accentuates epithelial to mesenchymal transition in obliterative bronchiolitis.

Bronchiolitis obliterans syndrome is characterized by fibrotic obliteration of small airways which severely impairs graft function and survival after lung transplantation. Bronchial epithelial cells from the transplanted lung can undergo epithelial to mesenchymal transition and this can be accentuated by activated macrophages. Macrophages demonstrate significant plasticity and change phenotype in response to their microenvironment. In this study we aimed to identify secretory products from macrophages that might be therapeutic targets for limiting the inflammatory accentuation of epithelial to mesenchymal transition in bronchiolitis obliterans syndrome. TNFα, IL-1ß and IL-8 are elevated in bronchoalveolar lavage from lung transplant patients prior to diagnosis of bronchiolitis obliterans syndrome. Classically activated macrophages secrete more TNFα and IL-1ß than alternatively activated macrophages and dramatically accentuate TGF-ß1-driven epithelial to mesenchymal transition in bronchial epithelial cells isolated from lung transplant patients. Blocking TNFα, but not IL-1ß, inhibits the accentuation of epithelial to mesenchymal transition. In a pilot unblinded therapeutic intervention in five patients with progressive bronchiolitis obliterans syndrome, anti-TNFα treatment improved forced expiratory volume in 1 second and 6-min walk distances in four patients. Our data identify TNFα as a potential new therapeutic target in bronchiolitis obliterans syndrome deserving of a randomized placebo controlled clinical trial.

Anti-reflux surgery in lung transplant recipients: outcomes and effects on quality of life.

Fundoplication may improve survival after lung transplantation. Little is known about the effects of fundoplication on quality of life in these patients. The aim of this study was to assess the safety of fundoplication in lung transplant recipients and its effects on quality of life. Between June 1, 2008 and December 31, 2010, a prospective study of lung transplant recipients undergoing fundoplication was undertaken. Quality of life was assessed before and after surgery. Body mass index (BMI) and pulmonary function were followed up. 16 patients, mean ± sd age 38 ± 11.9 yrs, underwent laparoscopic Nissen fundoplication. There was no peri-operative mortality or major complications. Mean ± SD hospital stay was 2.6 ± 0.9 days. 15 out of 16 patients were satisfied with the results of surgery post fundoplication. There was a significant improvement in reflux symptom index and DeMeester questionnaires and gastrointestinal quality of life index scores at 6 months. Mean BMI decreased significantly after fundoplication (p = 0.01). Patients operated on for deteriorating lung function had a statistically significant decrease in the rate of lung function decline after fundoplication (p = 0.008). Laparoscopic fundoplication is safe in selected lung transplant recipients. Patient benefit is suggested by improved symptoms and satisfaction. This procedure is acceptable, improves quality of life and may reduce deterioration of lung function.

Volatile biomarkers of Pseudomonas aeruginosa in cystic fibrosis and noncystic fibrosis bronchiectasis.

AIMS: The purpose of this study was to determine whether volatile organic compounds specific to Pseudomonas aeruginosa could be detected in clinical sputum specimens. METHODS AND RESULTS: Patients were recruited from specialist bronchiectasis and cystic fibrosis clinics. The gold standard for diagnosing Ps. aeruginosa infection was a positive sputum culture. About 72 sputum headspace samples taken from patients at risk of or known to have prior Ps. aeruginosa infection were analysed by solid phase micro-extraction mass spectrometry. 2-nonanone was a marker in Ps. aeruginosa in sputum headspace gas with sensitivity of 72% and specificity of 88%. A combination of volatile compounds, a sputum library of 17 compounds with 2-nonanone, increased sensitivity in the detection of Ps. aeruginosa to 91% with specificity of 88%. CONCLUSIONS: In contrast to the 48-hour turnaround for classical microbiological culture, these results were available within 1-2 h. These data demonstrate the potential for rapid and accurate diagnosis of Ps. aeruginosa infection from sputum samples. SIGNIFICANCE AND IMPACT OF THE STUDY: 2-Nonanone is a compound requiring further study in the exhaled breath as it may improve diagnostic of Ps. aeruginosa infection when combined with other reported volatile markers.

Raised interleukin-17 is immunolocalised to neutrophils in cystic fibrosis lung disease.

Interleukin (IL)-17 is pivotal in orchestrating the activity of neutrophils. Neutrophilic inflammation is the dominant pathology in cystic fibrosis (CF) lung disease. We investigated IL-17 protein expression in the lower airway in CF, its cellular immunolocalisation and the effects of IL-17 on CF primary bronchial epithelial cells. Immunohistochemistry was performed on explanted CF lungs and compared with the non-suppurative condition pulmonary hypertension (PH). Airway lavages and epithelial cultures were generated from explanted CF lungs. Immunoreactivity for IL-17 was significantly increased in the lower airway epithelium in CF (median 14.1%) compared with PH (2.95%, p=0.0001). The number of cells staining positive for IL-17 in the lower airway mucosa was also increased (64 cells·mm(-1) compared with 9 cells·mm(-1) basement membrane, p=0.0005) and included both neutrophils in addition to mononuclear cells. IL-17 was detectable in airway lavages from explanted CF lungs. Treatment of epithelial cultures with IL-17 increased production of IL-8, IL-6 and granulocyte macrophage colony-stimulating factor. In conclusion, immunoreactive IL-17 is raised in the lower airway of people with CF and localises to both neutrophils and mononuclear cells. IL-17 increases production of pro-neutrophilic mediators by CF epithelial cells, suggesting potential for a positive feedback element in airway inflammation.

Inflammation and epithelial to mesenchymal transition in lung transplant recipients: role in dysregulated epithelial wound repair.

Epithelial to mesenchymal transition (EMT) has been implicated in the pathogenesis of obliterative bronchiolitis (OB) after lung transplant. Although TNF-alpha accentuates TGF-beta1 driven EMT in primary human bronchial epithelial cells (PBECs), we hypothesized that other acute pro-inflammatory cytokines elevated in the airways of patients with OB may also accentuate EMT and contribute to dysregulated epithelial wound repair. PBECs from lung transplant recipients were stimulated with TGF-beta1+/-IL-1beta, IL-8, TNF-alpha or activated macrophages in co-culture and EMT assessed. The quality and rate of wound closure in a standardized model of lung epithelial injury was assessed in response to above stimuli. Co-treatment with TGF-beta1+TNF-alpha or IL-1beta significantly accentuates phenotypic and some functional features of EMT compared to TGF-beta1 alone. Co-treatment with TGF-beta1+TNF-alpha or IL-1beta accelerates epithelial wound closure however the quality of repair is highly dysregulated. Co-treatment with TGF-beta1+IL-8 has no significant effect on EMT or the speed or quality of wound healing. Activated macrophages dramatically accentuate TGF-beta1-driven EMT and cause dysregulated wound repair. Crosstalk between macrophage-derived acute inflammation in the airway and elevated TGF-beta1 may favor dysregulated airway epithelial repair and fibrosis in the lung allograft via EMT.

Epithelial to mesenchymal transition (EMT) and airway remodelling after human lung transplantation.

BACKGROUND: Aberrant epithelial repair is a key event in the airway remodelling which characterises obliterative bronchiolitis (OB) in the transplanted lung. The potential for airway epithelium from lung transplant recipients to undergo epithelial to mesenchymal cell transition (EMT) was assessed in culture and in vivo in lung allograft tissue. METHODS: Change in epithelial and mesenchymal marker expression was assessed after stimulation with transforming growth factor beta(1) (TGF-beta(1)) alone or in combination with tumour necrosis factor alpha (TNFalpha) and compared with untreated controls. The ability of cells to deposit extracellular matrix, secrete matrix metalloproteinases (MMPs) and invade collagen was investigated. Immunolocalisation of epithelial and mesenchymal markers was compared in airway tissue from stable recipients and those with OB. RESULTS: Untreated cells maintained epithelial morphology and phenotype. TGF-beta(1) reduced expression of epithelial markers, increased expression of vimentin and fibronectin, promoted collagen I and fibronectin deposition and increased MMP-9 production. Co-treatment with TNFalpha dramatically accentuated phenotypic and some functional features of EMT. Airway epithelial biopsies from recipients with OB demonstrated significantly increased staining for mesenchymal markers and significantly reduced E-cadherin staining compared with stable recipients. CONCLUSIONS: These observations demonstrate the ability of human airway epithelium to undergo EMT and suggest this phenomenon may be a potential link between inflammatory injury and TGF-beta(1)-driven airway remodelling in the development of OB.

Bronchial epithelial cells cultured from clinically stable lung allograft patients promote the development of macrophages from monocytes rather than dendritic cells.

BACKGROUND: It is understood that chronic allograft failure occurs as a result of alloimmune and non-alloimmune injury. Dendritic cells (DC) are thought to be crucial in regulating (allo)immune airway damage and interactions with epithelial cells are likely. Studies in human lung transplantation are limited, however, and the available literature on DC is inconsistent. This study focused on the ex vivo influence of primary bronchial epithelial cells derived from lung allografts on DC differentiation. METHODS: Epithelial cell conditioned media (ECCM) were added to monocytes differentiating into DC under the influence of interleukin-4 and granulocyte macrophage-colony stimulating factor. The resultant cells were compared with DC cultured without ECCM and with monocyte-derived macrophages. Expression of typical DC (eg, CD1a) and macrophage (eg, CD14) markers was assessed by flow cytometry. Phenotypical assessments were complemented by functional studies of mannose receptor-mediated phagocytosis (FITC-dextran uptake) and antigen-presenting capability (mixed lymphocyte reactions). RESULTS: Cells exposed to ECCM expressed significantly lower levels of CD1a than unexposed DC. CD14 expression and phagocytic function were increased. ECCM cultured cells also expressed lower levels of T cell co-stimulatory molecules, secreted an anti-inflammatory cytokine profile and had significantly reduced antigen-presenting capability. CONCLUSION: Using phenotypic and functional approaches, this study has shown that ECCM from lung allografts drives the production of macrophage-like cells from monocytes rather than DC. The data suggest that epithelial cells may restrain airway DC and potential alloimmunity. It is unclear whether the observed effect is specifically seen in lung transplant recipients or is a general property of bronchial epithelial cells. This may reflect a homeostatic inter-relationship between airway epithelial and DC populations relevant both to lung allografts and the lung more generally.

Pseudomembranous colitis in four patients with cystic fibrosis following lung transplantation.

In the present study, 4 patients with cystic fibrosis undergoing lung transplantation (from a total of 137) who developed fulminant pseudomembranous colitis are described. Initial presentation was variable and the mortality rate was 50% despite urgent colectomy. In one case the presenting abdominal distension was thought to be due to meconium ileus equivalent. It is concluded that Clostridium difficile colitis may be a difficult diagnosis in patients with cystic fibrosis and follows a fulminant course after lung transplantation.

Airway epithelial cell senescence in the lung allograft.

Chronic lung allograft dysfunction, manifesting as bronchiolitis obliterans syndrome (BOS), is characterized by airway epithelial injury, impaired epithelial regeneration and subsequent airway remodeling. Increased cellular senescence has been reported in renal and liver allografts affected by chronic allograft dysfunction but the significance of cellular senescence in the airway epithelium of the transplanted lung is unknown. Thirty-four lung transplant recipients, 20 with stable graft function and 14 with BOS, underwent transbronchial lung biopsy and histochemical studies for senescence markers in small airways. Compared to nontransplant control lung tissue (n = 9), lung allografts demonstrate significantly increased airway epithelial staining for senescence-associated beta galactosidase (SA beta-gal) (p = 0.0215), p16(ink4a) (p = 0.0002) and p21(waf1/cip) (p = 0.0138) but there was no difference in expression of these markers between stable and BOS affected recipients (p > 0.05). This preliminary cross-sectional study demonstrates that cellular senescence occurs with increased frequency in the airway epithelium of the lung allograft but does not establish any association between airway epithelial senescence and BOS. A prospective longitudinal study is required to better address any potential causal association between airway epithelial senescence in stable allograft recipients and the subsequent development of BOS.

Outcomes of lung transplantation for cystic fibrosis in a large UK cohort.

BACKGROUND: Lung transplantation is an important option to treat patients with advanced cystic fibrosis (CF) lung disease. The outcomes of a large UK cohort of CF lung transplantation recipients is reported. METHODS: Retrospective review of case notes and transplantation databases. RESULTS: 176 patients with CF underwent lung transplantation at our centre. The majority (168) had bilateral sequential lung transplantation. Median age at transplantation was 26 years. Diabetes was common pretransplantation (40%). Polymicrobial infection was common in individual recipients. A diverse range of pathogens were encountered, including the Burkholderia cepacia complex (BCC). The bronchial anastomotic complication rate was 2%. Pulmonary function (forced expiratory volume in 1 s % predicted) improved from a pretransplantation median of 0.8 l (21% predicted) to 2.95 l (78% predicted) at 1 year following transplantation. We noted an acute rejection rate of 41% within the first month. Our survival values were 82% survival at 1 year, 70% at 3 years, 62% at 5 years and 51% at 10 years. Patients with BCC infection had poorer outcomes and represented the majority of those who had a septic death. Data are presented on those free from these infections. Bronchiolitis obliterans syndrome (BOS) and sepsis were common causes of death. Freedom from BOS was 74% at 5 years and 38% at 10 years. Biochemical evidence of renal dysfunction was common although renal replacement was infrequently required (<5%). CONCLUSION: Lung transplantation is an important therapeutic option in patients with CF even in those with more complex microbiology. Good functional outcomes are noted although transplantation associated morbidities accrue with time.

Pseudomembranous colitis in four patients with cystic fibrosis following lung transplantation.

Pseudomembranous colitis is an uncommon complication in patients with cystic fibrosis, despite the use of multiple high-dose antibiotic regimens and the frequency of hospital admissions. Four patients from a total of 137 patients with cystic fibrosis undergoing lung transplantation are described who developed fulminant pseudomembranous colitis. Initial presentation was variable and the mortality rate was 50% despite urgent colectomy. In one case the presenting abdominal distension was thought to be due to meconium ileus equivalent. It is concluded that Clostridium difficile colitis may be a difficult diagnosis in patients with cystic fibrosis and follows a fulminant course after lung transplantation.

Primary airway epithelial cell culture from lung transplant recipients.

Long-term survival in lung transplantation is limited by the development of obliterative bronchiolitis, a condition characterised by inflammation, epithelial injury, fibroproliferation and obliteration of bronchioles leading to airflow obstruction. To investigate the role of the bronchial epithelium in the pathogenesis of obliterative bronchiolitis the current study aimed to establish primary bronchial epithelial cell cultures (PBEC) from lung allografts. Four to six bronchial brushings were obtained from sub-segmental bronchi of lung allografts. Cells were seeded onto collagen-coated plates and grown to confluence in bronchial epithelial growth medium. Bronchial brushings (n=33) were obtained from 27 patients. PBECs were grown to confluence from 12 out of 33 (39%) brushings. Failure to reach confluence was due to early innate infection. Bacteria were usually isolated from both bronchoalveolar lavage and culture media, but a separate population was identified in culture media only. Primary culture of bronchial epithelial cells from lung transplant recipients is feasible, despite a high rate of early, patient-derived infection. Latent infection of the allograft, identified only by bronchial brushings, may itself be a persistent stimulus for epithelial injury. This technique facilitates future mechanistic studies of airway epithelial responses in the pathogenesis of obliterative bronchiolitis.

Phenotype of airway epithelial cells suggests epithelial to mesenchymal cell transition in clinically stable lung transplant recipients.

BACKGROUND: Obliterative bronchiolitis in chronic rejection of lung allografts is characterised by airway epithelial damage and fibrosis. The process whereby normal epithelium is lost and replaced by fibroblastic scar tissue is poorly understood, but recent findings suggest that epithelial cells can become fibroblasts through epithelial-mesenchymal transition (EMT). It is hypothesised that EMT occurs in lung allografts and plays a potential role in airway remodelling. METHODS: Sixteen stable lung transplant recipients underwent bronchoscopy with bronchoalveolar lavage (BAL), endobronchial biopsies, and bronchial brushings. Biopsy sections were stained for the fibroblast marker S100A4. Brushings were cultured on collagen, stained with anti-S100A4, and examined for further EMT markers including matrix metalloproteinase (MMP) zymographic activity and epithelial invasion through collagen coated filters. RESULTS: A median 15% (0-48%) of the biopsy epithelium stained for S100A4 in stable lung transplant recipients and MMP-7 co-localisation was observed. In non-stimulated epithelial cultures from lung allografts, S100A4 staining was identified with MMP-2 and MMP-9 production and zymographic activity. MMP total protein and activity was increased following stimulation with transforming growth factor (TGF)-beta1. Non-stimulated transplant epithelial cells were invasive and penetration of collagen coated filters increased following TGF-beta1 stimulation. CONCLUSIONS: This study provides evidence of EMT markers in lung allografts of patients without loss of lung function. The EMT process may represent a final common pathway following injury in more common diseases characterised by airway remodelling.

Hypothesis: epithelial-to-mesenchymal transition is a common cause of chronic allograft failure.

Renal, hepatic, and lung allografts are compromised by aggressively deteriorating function. This chronic process is produced by an overall burden of organ damage, but the pathophysiology remains poorly understood. Rates of chronic rejection in the lung, for example, have not substantially improved over the last decade, despite new immunosuppressive drugs and improvements in surgical procedure. We present a hypothesis that epithelial-to-mesenchymal transition is a common cause of chronic allograft failure. Research in this area may provide insights into chronic rejection of kidney, liver, and lung allografts that impact on future therapeutic strategies.

Prevalence and clonality of Burkholderia cepacia complex genomovars in UK patients with cystic fibrosis referred for lung transplantation.

BACKGROUND: It has previously been reported that patients infected with Burkholderia cenocepacia (genomovar III) before lung transplantation have a poorer outcome than those with other B. cepacia complex infections. METHODS: An extensive study was conducted to determine the prevalence and clonality of B. cepacia complex genomovars isolated from patients referred for transplant assessment between 1989 to the present and, where appropriate, whether strain type was related to transplant outcome. RESULTS: Isolates from 29 patients were identified as B. cepacia complex organisms by molecular analysis. Thirteen patients (45%) were infected with the highly transmissible ET-12 strain of B. cenocepacia recA lineage III-A, while all remaining patients were infected with genetically unique B. cenocepacia, B. multivorans, and B. vietnamiensis strains. All previously reported deaths following transplantation were associated with ET-12 infection. CONCLUSIONS: The ET-12 strain is the predominant cause of B. cenocepacia infections in patients with cystic fibrosis referred to our pulmonary transplant centre and is associated with poor transplant outcomes using standard treatment regimens.