Successive influenza virus infection and Streptococcus pneumoniae stimulation alter human dendritic cell function

Background: Influenza virus is a major cause of respiratory disease worldwide and Streptococcus pneumoniae infection associated with influenza often leads to severe complications. Dendritic cells are key antigen presenting cells but its role in such co-infection is unclear.Methods: In this study, human monocyte derived-dentritic cells were either concurrently or successively challenged with the combination of live influenza virus and heat killed pneumococcus to mimic the viral pneumococcal infection. Dendritic cell viability, phenotypic maturation and cytokine production were then examined.Results: The challenge of influenza virus and pneumococcus altered dendritic cell functions dependent on the time interval between the successive challenge of influenza virus and pneumococcus, as well as the doses of pneumococcus. When dendritic cells were exposed to pneumococcus at 6 hr, but not 0 hr nor 24 hr after influenza virus infection, both virus and pneumococcus treated dendritic cells had greater cell apoptosis and expressed higher CD83 and CD86 than dendritic cells infected with influenza virus alone. Dendritic cells produced pro-inflammatory cytokines: TNF-α, IL-12 and IFN-γ synergistically to the successive viral and pneumococcal challenge. Whereas prior influenza virus infection suppressed the IL-10 response independent of the timing of the subsequent pneumococcal stimulation.Conclusions: Our results demonstrated that successive challenge of dendritic cells with influenza virus and pneumococcus resulted in synergistic up-regulation of pro-inflammatory cytokines with simultaneous down-regulation of anti-inflammatory cytokine, which may explain the immuno-pathogenesis of this important co-infection. © 2011 Wu et al; licensee BioMed Central Ltd.published_or_final_versio

Colour-barcoded magnetic microparticles for multiplexed bioassays

Encoded particles have a demonstrated value for multiplexed high-throughput bioassays such as drug discovery and clinical diagnostics(1,2). In diverse samples, the ability to use a large number of distinct identification codes on assay particles is important to increase throughput(3). Proper handling schemes are also needed to readout these codes on free-floating probe microparticles. Here we create vivid, free-floating structural coloured particles with multi-axis rotational control using a colour-tunable magnetic material and a new printing method(4). Our colour-barcoded magnetic microparticles offer a coding capacity easily into the billions with distinct magnetic handling capabilities including active positioning for code readouts and active stirring for improved reaction kinetics in microscale environments(5). A DNA hybridization assay is done using the colour-barcoded magnetic microparticles to demonstrate multiplexing capabilitiesclos

Programming magnetic anisotropy in polymeric microactuators

Polymeric microcomponents are widely used in microelectro-mechanical systems (MEMS) and lab-on-a-chip devices, but they suffer from the lack of complex motion, effective addressability and precise shape control(1,2). To address these needs, we fabricated polymeric nanocomposite microactuators driven by programmable heterogeneous magnetic anisotropy. Spatially modulated photopatterning(3) was applied in a shape-independent manner to microactuator components by successive confinement of self-assembled magnetic nanoparticles in a fixed polymer matrix. By freely programming the rotational axis of each component, we demonstrate that the polymeric microactuators can undergo predesigned, complex two- and three-dimensional motionclos