Thomas Geiser

Clinical and inflammatory characteristics of the European U-BIOPRED adult severe asthma cohort

U-BIOPRED is a European Union consortium of 20 academic institutions, 11 pharmaceutical companies and six patient organisations with the objective of improving the understanding of asthma disease mechanisms using a systems biology approach. This cross-sectional assessment of adults with severe asthma, mild/moderate asthma and healthy controls from 11 European countries consisted of analyses of patient-reported outcomes, lung function, blood and airway inflammatory measurements. Patients with severe asthma (nonsmokers, n=311; smokers/ex-smokers, n=110) had more symptoms and exacerbations compared to patients with mild/moderate disease (n=88) (2.5 exacerbations versus 0.4 in the preceding 12 months; p<0.001), with worse quality of life, and higher levels of anxiety and depression. They also had a higher incidence of nasal polyps and gastro-oesophageal reflux with lower lung function. Sputum eosinophil count was higher in severe asthma compared to mild/moderate asthma (median count 2.99% versus 1.05%; p=0.004) despite treatment with higher doses of inhaled and/or oral corticosteroids. Consistent with other severe asthma cohorts, U-BIOPRED is characterised by poor symptom control, increased comorbidity and airway inflammation, despite high levels of treatment. It is well suited to identify asthma phenotypes using the array of “omic” datasets that are at the core of this systems medicine approach. Severe asthma results in more airway inflammation, worse symptoms and lower lung function, despite increased therapy http://ow.ly/QznR3

In vivo Platelet Activation Is Increased during Sleep in Patients with Obstructive Sleep Apnea Syndrome

Background: Patients with obstructive sleep apnea syndrome (OSAS) have an increased risk of cardiovascular events including myocardial infarction and stroke. Objective: To determine whether in vivo platelet activation and the generation of procoagulant platelet-derived microparticles (PMP) are increased during sleep in patients with OSAS. Methods: In vivo platelet activation and PMP formation was determined using flow cytometry in 12 patients with untreated OSAS during and after sleep (4 and 7 a.m.). To study the effect of treatment with continuous positive airway pressure (CPAP), the measurements were repeated at the same time points after initiation of CPAP therapy. Healthy volunteers served as controls (n = 6). Results: Patients with OSAS had an increased percentage of platelets positive for the activation-dependent epitopes CD63 and CD62P during sleep (4 a.m.) compared to controls (4.8 ± 0.8 vs. 1.9 ± 0.4% for CD63, p < 0.01, and 2.0 ± 0.5 vs. 1.1 ± 0.3% for CD62P, p < 0.05). In OSAS patients, the amount of CD63- and CD62P-positive platelets was significantly elevated at 4 compared to 7 a.m. (4.8 ± 0.8 vs. 2.6 ± 0.4% for CD63 and 2.0 ± 0.5 vs. 1.1 ± 0.2% for CD62P, p < 0.05), but not in the control group. The levels of PMP were similar in patients with OSAS and controls at 4 and 7 a.m. After 1 night of CPAP therapy, there was a trend to reduced levels of CD63- and CD62P-positive platelets at 4 a.m. Conclusions: Patients with OSAS have increased in vivo platelet activation during sleep, which may contribute to the increased incidence of cardiovascular events in patients with OSAS.

Activation of human neutrophils by C3a and C5A Comparison of the effects on shape changes, chemotaxis, secretion, and respiratory burst

The effects of anaphylatoxin C3a on human neutrophils were studied in comparison with C5a. Both peptides induced a transient shape change response and a respiratory burst. In both cases C3a was 50‐ to 100‐times less potent than C5a. A marked chemotactic response with bimodal concentration dependence was obtained with C5a, but no neutrophil chemotaxis was observed with C3a. Repeated stimulation led to homologous desensitization of shape changes and respiratory burst but no cross‐desensitization, indicating that the two anaphylatoxins act through separate receptors. The lack of chemotactic activity suggests that C3a is not involved in neutrophil recruitment into infected or inflamed tissues.

Mechanisms of Cerebrovascular Events as Assessed by Procoagulant Activity, Cerebral Microemboli, and Platelet Microparticles in Patients With Prosthetic Heart Valves

BACKGROUND AND PURPOSE Cerebrovascular events (CVE) in patients with prosthetic heart valves (PHV) have remained a severe and frequent complication despite oral anticoagulation with or without aspirin. We studied the possible pathophysiological involvement of platelet-derived microparticles (PMP) as a contributing factor for the increased incidence of CVE in patients with PHV. METHODS We compared in a retrospective, case-control study the clinical outcome after the implantation of the PHV with several different independent morphological and functional methods, including simultaneous transcranial Doppler monitoring of both middle cerebral arteries, PMP detection by flow cytometry with use of platelet-specific antibodies, coagulation markers, and determination of the procoagulant activity by Russells viper venom time, a phospholipid-dependent coagulation assay. RESULTS Eight of 26 patients with PHV had 9 CVE during 136 person-years of observation. Transcranial Doppler monitoring revealed an increased frequency of microembolic signals recorded over a 30-minute period in patients with CVE (75+/-25; median, 55; range, 27 to 248) compared with those without CVE (23+/-12; median, 7; range, 0 to 153; P<0.05) or with control subjects (0; P<0.001). Flow cytometry analysis showed increased levels of PMP in patients with compared to those without CVE (4.1+/-0.6% versus 2.4+/-0.4% of all fluorescence-positive events gated; P<0.05). Increased procoagulant activity was documented by the shortened Russells viper venom time expressed as an increased level of platelet equivalents per microliter of plasma in patients compared with control subjects (+24.7+/-14.9%; P<0.01). Subgroup analysis revealed that patients with CVE had a higher excess of platelet equivalents per microliter of plasma than patients without CVE in relation to the controls (+68.7+/-36.7%; P<0.05). Mildly elevated thrombin-antithrombin III complexes (2.9+/-0.7; median, 2.3; normal, <2.0 microg/L) suggested incompletely suppressed thrombin formation, and fibrin generation (fibrinopeptide A) was in the upper normal range (2.1+/-0.2; median, 1.8; normal, <2.0 ng/mL), despite adequate anticoagulation (INR=3.6+/-0.1). CONCLUSIONS Our data show increased microembolic signals, platelet microparticles, and procoagulant activity in symptomatic patients with PHV and provide a potential pathophysiological explanation of CVE.

Pseudomonas aeruginosa ExoT inhibits in vitro lung epithelial wound repair

The nosocomial pathogen Pseudomonas aeruginosa causes clinical infection in the setting of pre‐existing epithelial tissue damage, an association that is mirrored by the increased ability of P. aeruginosa to bind, invade and damage injured epithelial cells in vitro. In this study, we report that P. aeruginosa inhibits the process of epithelial wound repair in vitro through the type III‐secreted bacterial protein ExoT, a GTPase‐activating protein (GAP) for Rho family GTPases. This inhibition primarily targets cells at the edge of the wound, and causes actin cytoskeleton collapse, cell rounding and cell detachment. ExoT‐dependent inhibition of wound repair is mediated through the GAP activity of this bacterial protein, as mutations in ExoT that alter the conserved arginine (R149) within the GAP domain abolish the ability of P. aeruginosa to inhibit wound closure. Because ExoT can also inhibit P. aeruginosa internalization by phagocytes and epithelial cells, this protein may contribute to the in vivo virulence of P. aeruginosa by allowing organisms both to overcome local host defences, such as an intact epithelial barrier, and to evade phagocytosis by immune effector cells.

Combined Determination of the Chemical Composition and of Health Effects of Secondary Organic Aerosols: The POLYSOA Project

Epidemiological studies show a clear link between increased mortality and enhanced concentrations of ambient aerosols. The chemical and physical properties of aerosol particles causing these health effects remain unclear. A major fraction of the ambient aerosol particle mass is composed of secondary organic aerosol (SOA). Recent studies showed that a significant amount of SOA consists of high molecular weight compounds (oligomers), which are chemically not well characterized. Within the POLYSOA project a large variety of state-of-the-art analytical chemical methods were used to characterize the chemical composition of SOA particles with emphasis on the oligomeric mass fraction. Mass spectrometric results showed that SOA oligomers are highly oxidized compounds and that hydroperoxides are formed, which is consistent with NMR results. This high molecular weight fraction accounts for up to 23% of the total organic carbon in SOA particles. These well-characterized SOA particles were deposited on three lung cell culture systems (microdissected respiratory epithelia from porcine tracheae, the human bronchial epithelial cell line BEAS-2B, and porcine lung surface macrophages obtained by bronchoalveolar lavage) in a newly constructed particle deposition chamber with the goal to eventually identify particle components that are responsible for cell responses leading to adverse health effects. In addition, monolayers of the alveolar epithelial cell line A549 were used in an alveolar epithelial repair model. The lung cells were examined for morphological, biochemical, and physiological changes after exposure to SOA. Analyses of the lung cells after exposure to SOA are ongoing. First data give evidence for a moderate increase of necrotic cell death as measured by lactate dehydrogenase release and for effects on the alveolar epithelial wound repair mainly due to alterations of cell spreading and cell migration at the edge of the wound. Thus, these first results indicate that SOA, in concentrations comparable to environmental concentrations, may induce distinct effects in lung cells.

Biomedical nanoparticles modulate specific CD4+ T cell stimulation by inhibition of antigen processing in dendritic cells

Abstract Understanding how nanoparticles may affect immune responses is an essential prerequisite to developing novel clinical applications. To investigate nanoparticle-dependent outcomes on immune responses, dendritic cells (DCs) were treated with model biomedical poly(vinylalcohol)-coated super-paramagnetic iron oxide nanoparticles (PVA-SPIONs). PVA-SPIONs uptake by human monocyte-derived DCs (MDDCs) was analyzed by flow cytometry (FACS) and advanced imaging techniques. Viability, activation, function, and stimulatory capacity of MDDCs were assessed by FACS and an in vitro CD4+ T cell assay. PVA-SPION uptake was dose-dependent, decreased by lipopolysaccharide (LPS)-induced MDDC maturation at higher particle concentrations, and was inhibited by cytochalasin D pre-treatment. PVA-SPIONs did not alter surface marker expression (CD80, CD83, CD86, myeloid/plasmacytoid DC markers) or antigen-uptake, but decreased the capacity of MDDCs to process antigen, stimulate CD4+ T cells, and induce cytokines. The decreased antigen processing and CD4+ T cell stimulation capability of MDDCs following PVA-SPION treatment suggests that MDDCs may revert to a more functionally immature state following particle exposure.

Cellular Responses after Exposure of Lung Cell Cultures to Secondary Organic Aerosol Particles

The scope of this work was to examine in vitro responses of lung cells to secondary organic aerosol (SOA) particles, under realistic ambient air and physiological conditions occurring when particles are inhaled by mammals, using a novel particle deposition chamber. The cell cultures included cell types that are representative for the inner surface of airways and alveoli and are the target cells for inhaled particles. The results demonstrate that an exposure to SOA at ambient-air concentrations of about 10(4) particles/cm(3) for 2 h leads to only moderate cellular responses. There is evidence for (i) cell type specific effects and for (ii) different effects of SOA originating from anthropogenic and biogenic precursors, i.e. 1,3,5-trimethylbenzene (TMB) and alpha-pinene, respectively. There was no indication for cytotoxic effects but for subtle changes in cellular functions that are essential for lung homeostasis. Decreased phagocytic activity was found in human macrophages exposed to SOA from alpha-pinene. Alveolar epithelial wound repair was affected by TMB-SOA exposure, mainly because of altered cell spreading and migration at the edge of the wound. In addition, cellular responses were found to correlate with particle number concentration, as interleukin-8 production was increased in pig explants exposed to TMB-SOA with high particle numbers.

Alveolar derecruitment and collapse induration as crucial mechanisms in lung injury and fibrosis.

Idiopathic pulmonary fibrosis (IPF) and bleomycin-induced pulmonary fibrosis are associated with surfactant system dysfunction, alveolar collapse (derecruitment), and collapse induration (irreversible collapse). These events play undefined roles in the loss of lung function. The purpose of this study was to quantify how surfactant inactivation, alveolar collapse, and collapse induration lead to degradation of lung function. Design-based stereology and invasive pulmonary function tests were performed 1, 3, 7, and 14 days after intratracheal bleomycin-instillation in rats. The number and size of open alveoli was correlated to mechanical properties. Active surfactant subtypes declined by Day 1, associated with a progressive alveolar derecruitment and a decrease in compliance. Alveolar epithelial damage was more pronounced in closed alveoli compared with ventilated alveoli. Collapse induration occurred on Day 7 and Day 14 as indicated by collapsed alveoli overgrown by a hyperplastic alveolar epithelium. This pathophysiology was also observed for the first time in human IPF lung explants. Before the onset of collapse induration, distal airspaces were easily recruited, and lung elastance could be kept low after recruitment by positive end-expiratory pressure (PEEP). At later time points, the recruitable fraction of the lung was reduced by collapse induration, causing elastance to be elevated at high levels of PEEP. Surfactant inactivation leading to alveolar collapse and subsequent collapse induration might be the primary pathway for the loss of alveoli in this animal model. Loss of alveoli is highly correlated with the degradation of lung function. Our ultrastructural observations suggest that collapse induration is important in human IPF.

Diagnosis and management of chronic obstructive pulmonary disease: the swiss guidelines. Official guidelines of the Swiss Respiratory Society

The new Swiss Chronic Obstructive Pulmonary Disease (COPD) Guidelines are based on a previous version, which was published 10 years ago. The Swiss Respiratory Society felt the need to update the previous document due to new knowledge and novel therapeutic developments about this prevalent and important disease. The recommendations and statements are based on the available literature, on other national guidelines and, in particular, on the GOLD (Global Initiative for Chronic Obstructive Lung Disease) report. Our aim is to advise pulmonary physicians, general practitioners and other health care workers on the early detection and diagnosis, prevention, best symptomatic control, and avoidance of COPD as well as its complications and deterioration.