Burkholderia cenocepacia ET12 strain activates TNFR1 signalling in cystic fibrosis airway epithelial cells

Burkholderia cenocepacia is an important pulmonary pathogen in individuals with cystic fibrosis (CF). Infection is often associated with severe pulmonary inflammation, and some patients develop a fatal necrotizing pneumonia and sepsis (‘cepacia syndrome’). The mechanisms by which this species causes severe pulmonary inflammation are poorly understood. Here, we demonstrate that B. cenocepacia BC7, a potentially virulent representative of the epidemic ET12 lineage, binds to tumour necrosis factor receptor 1 (TNFR1) and activates TNFR1-related signalling pathway similar to TNF-α, a natural ligand for TNFR1. This interaction participates in stimulating a robust IL-8 production from CF airway epithelial cells. In contrast, BC45, a less virulent ET12 representative, and ATCC 25416, an environmental B. cepacia strain, do not bind to TNFR1 and stimulate only minimal IL-8 production from CF cells. Further, TNFR1 expression is increased in CF airway epithelial cells compared with non-CF cells. We also show that B. cenocepacia ET12 strain colocaizes with TNFR1 in vitro and in the lungs of CF patients who died due to infection with B. cenocepacia, ET12 strain. Together, these results suggest that interaction of B. cenocepacia , ET12 strain with TNFR1 may contribute to robust inflammatory responses elicited by this organism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73011/1/j.1462-5822.2007.01029.x.pd

Intracellular trafficking and replication of Burkholderia cenocepacia in human cystic fibrosis airway epithelial cells

We investigated the trafficking of Burkholderia cenocepacia , an opportunistic respiratory pathogen of persons with cystic fibrosis (CF), in immortalized CF airway epithelial cells in vitro . Our results indicate that bacteria enter cells in a process involving actin rearrangement. Whereas both live and heat-killed bacteria reside transiently in early endosomes, only live bacteria escape from late endosomes to colocalize in vesicles positive for lysosomal membrane marker LAMP1, endoplasmic reticulum (ER) membrane marker calnexin, and autophagosome marker monodansylcadavarine (MDC). Twenty-four hours after infection, microcolonies of live bacteria were observed in the perinuclear area colocalizing with calnexin. In contrast, after ingestion, dead bacteria colocalized with late endosome marker Rab7, and lysosome markers LAMP1 and cathepsin D, but not with calnexin or MDC. Six to eight hours after ingestion of dead bacteria, degraded bacterial particles were observed in the cytoplasm and in vesicles positive for cathepsin D. These results indicate that live B. cenocepacia gain entry into human CF airway cells by endocytosis, escape from late endosomes to enter autophagosomes that fail to fuse with mature lysosomes, and undergo replication in the ER. This survival and replication strategy may contribute to the capacity of B. cenocepacia to persist in the lungs of infected CF patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75744/1/j.1462-5822.2006.00724.x.pd

Effect of ivacaftor on mucociliary clearance and clinical outcomes in cystic fibrosis patients with G551D-CFTR

BACKGROUND: The ability to restore cystic fibrosis transmembrane regulator (CFTR) function with effective small molecule modulators in patients with cystic fibrosis provides an opportunity to study relationships between CFTR ion channel function, organ level physiology, and clinical outcomes. METHODS: We performed a multisite, prospective, observational study of ivacaftor, prescribed in patients with the G551D-CFTR mutation. Measurements of lung mucociliary clearance (MCC) were performed before and after treatment initiation (1 and 3 months), in parallel with clinical outcome measures. RESULTS: Marked acceleration in whole lung, central lung, and peripheral lung MCC was observed 1 month after beginning ivacaftor and was sustained at 3 months. Improvements in MCC correlated with improvements in forced expiratory volume in the first second (FEV1) but not sweat chloride or symptom scores. CONCLUSIONS: Restoration of CFTR activity with ivacaftor led to significant improvements in MCC. This physiologic assessment provides a means to characterize future CFTR modulator therapies and may help to predict improvements in lung function. TRIAL REGISTRATION: ClinicialTrials.gov, NCT01521338. FUNDING: CFF Therapeutics (GOAL11K1)

The growth and development of Clarke Chapman from 1864 to 1914

Clarke Chapman was the main supplier of leading-edge auxiliary equipment to the British shipbuilding industry before the First World War. Penrose's theory was used to examine the company's growth. The findings of this study show that the ownership structure and the governance of the family-owned firm shaped its growth path. Product expansion driven by financial slack was followed by the development of new capabilities as shipbuilding converted from sail to steam-power. The next phase was geographical and international expansion underpinned by human resource slack. Additional productive opportunities were created by recruiting specialist human resources and pursuing hybrid modes of growth