β1-Integrin Accumulates in Cystic Fibrosis Luminal Airway Epithelial Membranes and Decreases Sphingosine, Promoting Bacterial Infections

Chronic pulmonary colonization with bacterial pathogens, particularly Pseudomonas aeruginosa, is the primary cause of morbidity and mortality in patients with cystic fibrosis (CF). We observed that β1-integrins accumulate on the luminal membrane of upper-airway epithelial cells from mice and humans with CF. β1-integrin accumulation is due to increased ceramide and the formation of ceramide platforms that trap β1-integrins on the luminal pole of bronchial epithelial cells. β1-integrins downregulate acid ceramidase expression, resulting in further accumulation of ceramide and consequent reduction of surface sphingosine, a lipid that kills bacteria. Interrupting this vicious cycle by triggering surface β1-integrin internalization via anti-β1-integrin antibodies or the RGD peptide ligand-or by genetic or pharmacological correction of ceramide levels-normalizes β1-integrin distribution and sphingosine levels in CF epithelial cells and prevents P. aeruginosa infection in CF mice. These findings suggest a therapeutic avenue to ameliorate CF-associated bacterial infections.

Glucosylceramide Critically Contributes to the Host Defense of Cystic Fibrosis Lungs

BACKGROUND

Cystic fibrosis (CF) is the most common autosomal-recessive disorder in western countries. Previous studies have demonstrated an important role of sphingolipids in the pathophysiology of cystic fibrosis. It has been shown that ceramide has a central role in various pulmonary infections, including those with Pseudomonas aeruginosa (P. aeruginosa). Ceramide is accumulated in the airways of CF mice and patients. However, little is known about a potential role of glucosylceramide in cystic fibrosis.

METHODS

We investigated the expression of glucosylceramide and lactosylceramide in the respiratory tract of murine and human CF samples by immunohistochemistry and analyzed effects of glucosylceramide on P. aeruginosa in vitro. We performed pulmonary infections with P. aeruginosa and tested inhalation with glucosylceramide.

RESULTS

We demonstrate that glucosylceramide is down-regulated on the apical surface of bronchial and tracheal epithelial cells in cystic fibrosis mice. Although glucosylceramide did not have a direct bactericidal effect on Pseudomonas aeruginosa in vitro, inhalation of CF mice with glucosylceramide protected these mice from infection with P. aeruginosa, while non-inhaled CF mice developed severe pneumonia.

CONCLUSION

Our data suggest that glucosylceramide acts in vivo in concert with ceramide and sphingosine to determine the pulmonary defense against P. aeruginosa.

An association of particulate air pollution and traffic exposure with mortality after lung transplantation in Europe

Air pollution from road traffic is a serious health risk, especially for susceptible individuals. Single-centre studies showed an association with chronic lung allograft dysfunction (CLAD) and survival after lung transplantation, but there are no large studies.13 lung transplant centres in 10 European countries created a cohort of 5707 patients. For each patient, we quantified residential particulate matter with aerodynamic diameter ≤10 µm (PM₁₀) by land use regression models, and the traffic exposure by quantifying total road length within buffer zones around the home addresses of patients and distance to a major road or freeway.After correction for macrolide use, we found associations between air pollution variables and CLAD/mortality. Given the important interaction with macrolides, we stratified according to macrolide use. No associations were observed in 2151 patients taking macrolides. However, in 3556 patients not taking macrolides, mortality was associated with PM₁₀ (hazard ratio 1.081, 95% CI 1.000-1.167); similarly, CLAD and mortality were associated with road lengths in buffers of 200-1000 and 100-500 m, respectively (hazard ratio 1.085- 1.130). Sensitivity analyses for various possible confounders confirmed the robustness of these associations.Long-term residential air pollution and traffic exposure were associated with CLAD and survival after lung transplantation, but only in patients not taking macrolides.

Decreased Hypercapnic Ventilatory Response in Long-Term Lung Transplant Recipients is Associated with Exercise Impairment

PURPOSE

Bilateral lung transplantation results in complete denervation of the lung and might impair hypercapnic ventilatory response (HCVR). However, experimental and clinical findings are scarce and conflicting. Therefore, this study investigated the relationship between HCVR and exercise capacity after long-term bilateral lung transplantation.

METHODS

This cross-sectional analysis enrolled 46 bilateral lung transplant recipients between October 2011 and July 2012 who underwent cardiopulmonary exercise testing to evaluate maximum workload, and carbon dioxide (CO2) rebreathing. CO2 rebreathing was also evaluated in 35 control subjects.

RESULTS

In lung transplant recipients age was 54 ± 11 years, body mass index (BMI) 25.4 ± 4.1 kg/m(2), and time after transplantation 4.5 ± 2.5 years (range 9 months to 10 years). Controls were aged 41 ± 12 years and had a BMI of 24.9 ± 4.0 kg/m(2). There were significant differences between lung transplant recipients and controls in forced expiratory volume in 1 s (76 ± 22 vs. 94 ± 12 % predicted, p < 0.001) and inspiratory vital capacity (91 ± 20 vs. 105 ± 14 % predicted, p = 0.001). Blood gases did not differ significantly in patients versus controls. HCVR in lung transplant recipients was 1.44 ± 1.07 L/min/mmHg compared with 2.09 ± 1.14 L/min/mmHg in controls (p = 0.001). Exercise capacity in lung transplant recipients (73 ± 24 W) was 49 % predicted. Linear regression analysis showed that exercise capacity was significantly associated with HCVR. A 1 L/min/mmHg decrease in HCVR decreased exercise capacity by 50 W.

CONCLUSION

HCVR is reduced in long-term bilateral lung transplant recipients and this might explain the observed impairment of exercise capacity.

Comparison of a New Miniaturized Extracorporeal Membrane Oxygenation System With Integrated Rotary Blood Pump to a Standard System in a Porcine Model of Acute Lung Injury

Extracorporeal membrane oxygenation (ECMO) is used for severe acute respiratory distress syndrome. However, available ECMO systems are large and not well designed for fast delivery, emergency implantation, and interhospital transfer. Therefore, a new miniaturized oxygenator with integrated rotary blood pump (ILIAS) was developed and compared with a standard ECMO system in a large animal model. Acute lung injury was induced with repeated pulmonary saline lavage in 14 pigs until PaO2 /FiO2 -ratio was <100 mm Hg with a positive-end-expiratory-pressure of 5 mbar. Pigs were assigned to the following three groups: group 1 (n = 4): control group with conventional ventilation; group 2 (n = 5): standard vv-ECMO; group 3 (n = 5): vv-ILIAS. Gas exchange, hemodynamics, hemolysis, and coagulation activation were examined over a period of 8 h. No device failed during the observation period. PaCO2 decreased from 59.40 ± 4.14 mm Hg to 48.62 ± 4.50 mm Hg after 1 h in the ILIAS group compared with an improvement of PaCO2 from 48.86 ± 7.45 to 40.10 ± 6.02 in the conventional ECMO group (P = not significant [n.s.]). ARDS-induced respiratory acidosis was controlled promptly with a pH of 7.2 ± 0.1 at baseline increasing to 7.4 ± 0.1 in both study groups after 60 min of ECMO support. Mean carbon dioxide transfer was comparable between the conventional ECMO and ILIAS (211.36 ± 78.39 mL/min vs. 219.99 ± 76.72 mL/min, P = n.s.). PaO2 /FiO2 increased from 118.4 ± 15.5 mm Hg to 179.1 ± 72.4 mm Hg in the ILIAS group compared with an improvement of oxygenation from 107.1 ± 24.9 mm Hg to 179.0 ± 45.7 mm Hg in the standard ECMO group (P = n.s.). Mean oxygen transfer was calculated with 136.09 ± 30.25 mL/min for the ILIAS and 129.05 ± 36.28 mL/min for the standard ECMO. Hemodynamic instability or significant activation of the plasmatic coagulation was not observed. However, hemolysis was significantly higher in the ILIAS group compared with the conventional ECMO. As the ILIAS prototype provided excellent gas exchange with hemodynamic stability comparable with a standard ECMO system, we believe this study serves as a proof of concept. Further development and design modifications (optimized rotation speed and surface coating of rotor) are already done and another experiment is projected to reduce hemolysis and platelet consumption for clinical application.

Does Traumatic Donor Cause of Death Influence Outcome after Lung Transplantation? A Single-Centre Analysis

Background Owing to the shortage of donor organs in lung transplantation (LuTX), liberalization of donor selection criteria has been proposed. However, some studies suggested that donor traumatic brain damage might influence posttransplantation allograft function. This article aimed to investigate the association of donor cause of death (DCD) and outcome after LuTX.

Methods A retrospective analysis of 186 consecutive double LuTXs at our institution from January 2000 to December 2008 was performed. DCD was categorized into traumatic brain injury (TBI) and nontraumatic brain injury (NTBI). In addition, NTBI was sub classified as spontaneous intracerebral bleeding (B), hypoxic brain damage (H), and intracerebral neoplasia (N).

Results DCD was classified as TBI in 50 patients (26.9%) and NTBI in 136 patients (73.1%): B in 112 patients (60.2%), H in 21 patients (11.3%), and N in 3 patients (1.6%). Young male donors predominated in group TBI (mean age 36.0 ± 14.5 vs. 42.8 ± 10.7, p < 0.01; 29 males in the TBI group [58.0%] vs. 48 males in the NTBI group [35.3%], p < 0.01). Groups of DCD did not differ significantly by recipient age or gender, recipient diagnosis, donor ventilation time, or paO2/FiO2 before harvesting. TBI donors received significantly more blood (3.4 ± 3.8 vs. 1.8 ± 1.9, p = 0.03). A chest trauma was evident only in group T (n = 7 [3.7%] vs. 0 [0%], p < 0.001). Mode of donor death did not affect the following indices of graft function: length of postoperative ventilation, paO2/FiO2 ratio up to 48 hours, and lung function up to 36 months. One- and three-year survival was comparable with 84.4 and 70.4% for TBI donors versus 89.4% and 69.2% for NTBI donors. Five-year survival tended to be lower in the TBI group but did not reach statistical significance (43.4 vs. 53.9%).

Conclusion This study indicates that traumatic DCD does not affect outcome after LuTX. These results can be achieved with an ideal donor management combined with an individual case-to-case evaluation by an experienced LuTX surgeon.

Atrial Fibrillation Activates AMP-Dependent Protein Kinase and its Regulation of Cellular Calcium Handling: Potential Role in Metabolic Adaptation and Prevention of Progression

BACKGROUND

Atrial fibrillation (AF) is associated with metabolic stress, which activates adenosine monophosphate-regulated protein kinase (AMPK).

OBJECTIVES

This study sought to examine AMPK response to AF and associated metabolic stress, along with consequences for atrial cardiomyocyte Ca(2+) handling.

METHODS

Calcium ion (Ca(2+)) transients (CaTs) and cell shortening (CS) were measured in dog and human atrial cardiomyocytes. AMPK phosphorylation and AMPK association with Ca(2+)-handling proteins were evaluated by immunoblotting and immunoprecipitation.

RESULTS

CaT amplitude and CS decreased at 4-min glycolysis inhibition (GI) but returned to baseline at 8 min, suggesting cellular adaptation to metabolic stress, potentially due to AMPK activation. GI increased AMPK-activating phosphorylation, and an AMPK inhibitor, compound C (CompC), abolished the adaptation of CaT and CS to GI. The AMPK activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) increased CaT amplitude and CS, restoring CompC-induced CaT and CS decreases. CompC decreased L-type calcium channel current (ICa,L), along with ICa,L-triggered CaT amplitude and sarcoplasmic reticulum (SR) Ca(2+) content under voltage clamp conditions in dog cells and suppressed CaT and ICa,L in human cardiomyocytes. Small interfering ribonucleic acid-based AMPK knockdown decreased CaT amplitude in neonatal rat cardiomyocytes. L-type Ca(2+) channel α subunits coimmunoprecipitated with AMPKα. Atrial AMPK-activating phosphorylation was enhanced by 1 week of electrically maintained AF in dogs; fractional AMPK phosphorylation was increased in paroxysmal AF and reduced in longstanding persistent AF patients.

CONCLUSIONS

AMPK is activated by metabolic stress and AF, and helps maintain the intactness of atrial ICa,L, Ca(2+) handling, and cell contractility. AMPK contributes to the atrial compensatory response to AF-related metabolic stress; AF-related metabolic responses may be an interesting new therapeutic target.

Bacteria detected in the honeybee parasitic mite Varroa destructor collected from beehive winter debris

AIMS

The winter beehive debris containing bodies of honeybee parasitic mite Varroa destructor is used for veterinary diagnostics. The Varroa sucking honeybee haemolymph serves as a reservoir of pathogens including bacteria. Worker bees can pick up pathogens from the debris during cleaning activities and spread the infection to healthy bees within the colony. The aim of this study was to detect entomopathogenic bacteria in the Varroa collected from the winter beehive debris.

METHODS AND RESULTS

Culture-independent approach was used to analyse the mite-associated bacterial community. Total DNA was extracted from the samples of 10 Varroa female individuals sampled from 27 different sites in Czechia. The 16S rRNA gene was amplified using universal bacterial primers, cloned and sequenced, resulting in a set of 596 sequences representing 29 operational taxonomic units (OTU97). To confirm the presence of bacteria in Varroa, histological sections of the mites were observed. Undetermined bacteria were observed in the mite gut and fat tissue.

CONCLUSION

Morganella sp. was the most frequently detected taxon, followed by Enterococcus sp., Pseudomonas sp., Rahnella sp., Erwinia sp., and Arsenophonus sp. The honeybee putative pathogen Spiroplasma sp. was detected at one site and Bartonella-like bacteria were found at four sites. PCR-based analysis using genus-specific primers enabled detection of the following taxa: Enterococcus, Bartonella-like bacteria, Arsenophonus and Spiroplasma.

SIGNIFICANCE AND IMPACT OF THE STUDY

We found potentially pathogenic (Spiroplasma) and parasitic bacteria (Arsenophonus) in mites from winter beehive debris. The mites can be reservoirs of the pathogenic bacteria in the apicultures.

The cooling tube: A novel small animal model of systemic hypothermia in awake Syrian Golden Hamsters (mesocricetus auratus)

Hypothermia is increasingly used as a therapeutic strategy in a diversity of clinical scenarios. Its impact on mammalian physiology, particularly on the microcirculatory changes of critical organ systems, are, however, incompletely understood. Close examination of the literature reveals a marked paucity of small animal models of rapid systemic hypothermia. All published models introduce important microvascular confounders by investigating either local cooling processes or using anaesthetised animals. Here we present the first rapid systemic hypothermia model in an awake hamster. We developed a waterstream cooled copper tube system for standardized systemic temperature control. With this novel system core body temperature (Tc) in 14 awake animals could be precisely stabilised at temperatures of 30°C and 18°C (7 animals, respectively) within 10-20 min. Rewarming was achieved over 10-15 min. Tolerance of the procedure was excellent. Hamsters did not show any behavioural changes in the mild hypothermia group. In the deep hypothermia group 6 of 7 animals regained normal behaviour within 2-11 hs. As hypothermia was induced in dorsal skinfold chamber bearing animals this model seems suitable for investigation of microcirculatory purposes.Advantages over previously established experimental hypothermia models are significant. Amongst these, the possibility of visualization of microcirculation, the lack of microcirculation confounding factors such as anaesthetic drugs, the ability for precise Tc control and rapid induction of hypothermia are prominent.