Role of Bacterial Surface Structures on the Interaction of Klebsiella pneumoniae with Phagocytes

Phagocytosis is a key process of the immune system. The human pathogen Klebsiella pneumoniae is a well known example of a pathogen highly resistant to phagocytosis. A wealth of evidence demonstrates that the capsule polysaccharide (CPS) plays a crucial role in resistance to phagocytosis. The amoeba Dictyostelium discoideum shares with mammalian macrophages the ability to phagocytose and kill bacteria. The fact that K. pneumoniae is ubiquitous in nature and, therefore, should avoid predation by amoebae, poses the question whether K. pneumoniae employs similar means to counteract amoebae and mammalian phagocytes. Here we developed an assay to evaluate K. pneumoniae-D. discoideum interaction. The richness of the growth medium affected the threshold at which the cps mutant was permissive for Dictyostelium and only at lower nutrient concentrations the cps mutant was susceptible to predation by amoebae. Given the critical role of bacterial surface elements on host-pathogen interactions, we explored the possible contribution of the lipopolysaccharide (LPS) and outer membrane proteins (OMPs) to combat phagoyctosis by D. discoideum. We uncover that, in addition to the CPS, the LPS O-polysaccharide and the first core sugar participate in Klebsiella resistance to predation by D. discoideum. K. pneumoniae LPS lipid A decorations are also necessary to avoid predation by amoebae although PagP-dependent palmitoylation plays a more important role than the lipid A modification with aminoarabinose. Mutants lacking OMPs OmpA or OmpK36 were also permissive for D. discoideium growth. Except the LPS O-polysaccharide mutants, all mutants were more susceptible to phagocytosis by mouse alveolar macrophages. Finally, we found a correlation between virulence, using the pneumonia mouse model, and resistance to phagocytosis. Altogether, this work reveals novel K. pneumoniae determinants involved in resistance to phagocytosis and supports the notion that Dictyostelium amoebae might be useful as host model to measure K. pneumoniae virulence and not only phagocytosis. © 2013 March et al.

I can't get a breath: experiences of living with advanced chronic obstructive pulmonary disease

This study aims to explore the potential for palliative care among people living with advanced chronic obstructive pulmonary disease (COPD). Individual semi-structured interviews (n=13) were conducted with people who had a diagnosis of advanced COPD and were on optimal tolerated drug therapy, with their breathing volume (forced expiratory volume at less than 30%) or were on long-term oxygen therapy or non-invasion ventilation. Participants raised concerns about the uncertain trajectory of the illness and reported unmet palliative care needs with poor access to palliative care services. For most people, palliative care was associated with end of life; therefore, they were unwilling to discuss the issue. There was a wide acceptance that, medically, nothing more could be done. Findings also suggest that patients had unmet palliative care needs, requiring information and support. The research suggests the need for palliative care to be extended to all (regardless of diagnosis), with packages of care developed to target specific needs.

High population prevalence of cardiac troponin I measured by a high-sensitivity assay and cardiovascular risk estimation: the MORGAM Biomarker Project Scottish Cohort

Aims
Our aim was to test the prediction and clinical applicability of high-sensitivity assayed troponin I for incident cardiovascular events in a general middle-aged European population.

Methods and results
High-sensitivity assayed troponin I was measured in the Scottish Heart Health Extended Cohort (n = 15 340) with 2171 cardiovascular events (including acute coronary heart disease and probable ischaemic strokes), 714 coronary deaths (25% of all deaths), 1980 myocardial infarctions, and 797 strokes of all kinds during an average of 20 years follow-up. Detection rate above the limit of detection (LoD) was 74.8% in the overall population and 82.6% in men and 67.0% in women. Troponin I assayed by the high-sensitivity method was associated with future cardiovascular risk after full adjustment such as that individuals in the fourth category had 2.5 times the risk compared with those without detectable troponin I (P < 0.0001). These associations remained significant even for those individuals in whom levels of contemporary-sensitivity troponin I measures were not detectable. Addition of troponin I levels to clinical variables led to significant increases in risk prediction with significant improvement of the c-statistic (P < 0.0001) and net reclassification (P < 0.0001). A threshold of 4.7 pg/mL in women and 7.0 pg/mL in men is suggested to detect individuals at high risk for future cardiovascular events.

Conclusion
Troponin I, measured with a high-sensitivity assay, is an independent predictor of cardiovascular events and might support selection of at risk individuals.

Troponin I and cardiovascular risk prediction in the general population: the BiomarCaRE consortium

AIMS: Our aims were to evaluate the distribution of troponin I concentrations in population cohorts across Europe, to characterize the association with cardiovascular outcomes, to determine the predictive value beyond the variables used in the ESC SCORE, to test a potentially clinically relevant cut-off value, and to evaluate the improved eligibility for statin therapy based on elevated troponin I concentrations retrospectively.

METHODS AND RESULTS: Based on the Biomarkers for Cardiovascular Risk Assessment in Europe (BiomarCaRE) project, we analysed individual level data from 10 prospective population-based studies including 74 738 participants. We investigated the value of adding troponin I levels to conventional risk factors for prediction of cardiovascular disease by calculating measures of discrimination (C-index) and net reclassification improvement (NRI). We further tested the clinical implication of statin therapy based on troponin concentration in 12 956 individuals free of cardiovascular disease in the JUPITER study. Troponin I remained an independent predictor with a hazard ratio of 1.37 for cardiovascular mortality, 1.23 for cardiovascular disease, and 1.24 for total mortality. The addition of troponin I information to a prognostic model for cardiovascular death constructed of ESC SCORE variables increased the C-index discrimination measure by 0.007 and yielded an NRI of 0.048, whereas the addition to prognostic models for cardiovascular disease and total mortality led to lesser C-index discrimination and NRI increment. In individuals above 6 ng/L of troponin I, a concentration near the upper quintile in BiomarCaRE (5.9 ng/L) and JUPITER (5.8 ng/L), rosuvastatin therapy resulted in higher absolute risk reduction compared with individuals <6 ng/L of troponin I, whereas the relative risk reduction was similar.

CONCLUSION: In individuals free of cardiovascular disease, the addition of troponin I to variables of established risk score improves prediction of cardiovascular death and cardiovascular disease.