MiR-155 Induction by F. novicida but Not the Virulent F. tularensis Results in SHIP Down-Regulation and Enhanced Pro-Inflammatory Cytokine Response

The intracellular Gram-negative bacterium Francisella tularensis causes the disease tularemia and is known for its ability to subvert host immune responses. Previous work from our laboratory identified the PI3K/Akt pathway and SHIP as critical modulators of host resistance to Francisella. Here, we show that SHIP expression is strongly down-regulated in monocytes and macrophages following infection with F. tularensis novicida (F.n.). To account for this negative regulation we explored the possibility that microRNAs (miRs) that target SHIP may be induced during infection. There is one miR that is predicted to target SHIP, miR-155. We tested for induction and found that F.n. induced miR-155 both in primary monocytes/macrophages and in vivo. Using luciferase reporter assays we confirmed that miR-155 led to down-regulation of SHIP, showing that it specifically targets the SHIP 3′UTR. Further experiments showed that miR-155 and BIC, the gene that encodes miR-155, were induced as early as four hours post-infection in primary human monocytes. This expression was dependent on TLR2/MyD88 and did not require inflammasome activation. Importantly, miR-155 positively regulated pro-inflammatory cytokine release in human monocytes infected with Francisella. In sharp contrast, we found that the highly virulent type A SCHU S4 strain of Francisella tularensis (F.t.) led to a significantly lower miR-155 response than the less virulent F.n. Hence, F.n. induces miR-155 expression and leads to down-regulation of SHIP, resulting in enhanced pro-inflammatory responses. However, impaired miR-155 induction by SCHU S4 may help explain the lack of both SHIP down-regulation and pro-inflammatory response and may account for the virulence of Type A Francisella

Bacterial triggering of inflammation by intracellular sensors

Recognition of bacterial infection is the first key step to the initiation of an inflammatory response and host defense. Transmembrane proteins of the Toll-like receptor family have long been recognized as key detectors of the extracellular presence of pathogens. Recently, much research has identified a variety of intracellular detectors that also mediate innate immune responses following bacterial infection. These cannot only recognize bacteria that invade the cell cytoplasm, but also a variety of bacterial products that are introduced into cells by specialized secretion systems or are secreted toxins. This article will focus on these intracellular detectors and the bacterial components that they recognize. These detectors are particularly well adapted to recognize the presence of pathogenic bacteria as opposed to commensal organisms. Their growing importance suggests that targeting such intracellular pathways may be important in the future for manipulating the immune response to infection as an aid to augmenting host defense and providing more effective vaccines

Quantitative Proteomics Analysis of Macrophage-Derived Lipid Rafts Reveals Induction of Autophagy Pathway at the Early Time of Francisella tularensis LVS Infection

Francisella tularensis is a highly infectious intracellular pathogen that has evolved an efficient strategy to subvert host defense response to survive inside the host. The molecular mechanisms regulating these host-pathogen interactions and especially those that are initiated at the time of the bacterial entry via its attachment to the host plasma membrane likely predetermine the intracellular fate of pathogen. Here, we provide the evidence that infection of macrophages with F. tularensis leads to changes in protein composition of macrophage-derived lipid rafts, isolated as detergent-resistant membranes (DRMs). Using SILAC-based quantitative proteomic approach, we observed the accumulation of autophagic adaptor protein p62 at the early, stages of microbe-host cell interaction. We confirmed the colocalization of the p62 with ubiquitinated and LC3-decorated intracellular F. tularensis microbes with its maximum at 1 h postinfection. Furthermore, the infection of p62-knockdown host cells led to the transient increase in the intracellular number of microbes up to 4 h after in vitro infection. Together, these data suggest that the activation of the autophagy pathway in F. tularensis infected macrophages, which impacts the early phase of microbial proliferation, is subsequently circumvented by ongoing infection.</p

Nutritional condition of two coastal rocky fishes and the potential role of a marine protected area

Knowledge of the nutritional conditions of coastal commercial fish populations is key to understanding stock health status, and is essential when making reasonable exploitation and management plans. Here, we present the first results on the condition and feeding preferences of two coastal fish species, Diplodus sargus (Linnaeus, 1758) and Pagellus erythrinus (Linnaeus, 1758). Using stable isotope and biochemical analyses, we tested the potential effects of a marine protected area (MPA) and the occurrence of a dramatic coastal storm on the condition and quality of nutrition. The results suggest that both condition (lipids) and nutrition quality (fatty acids, FAs) in P. erythrinus and D. sargus depend upon on food availability in the area in which they were captured. Pagellus erythrinus individuals inside the MPA stored higher quantities of lipids [46.73 19.00 lg lipid mg organic matter (OM) 1] than those outside the MPA (15.63 5.30 lg lipid mg OM 1) only before the storm. Diplodus sargus showed different FA signatures inside and outside the MPA before and after the storm. These results suggest that D. sargus increased their quality of nutrition inside (16.62 3.17 lg FA mg OM 1) versus outside (7.88 2.36 lg FA mg OM 1) the MPA, owing to increased food diversity and availability. Conversely, P. erythrinus did not show differences in nutritional quality inside (18.12 1.13 lg FA mg OM 1) or outside (18.81 1.42 lg FA mg OM 1) the MPA, possibly because of the increase in ingestion not affecting the studied parameters. In P. erythrinus, the FA concentration decreased after the storm, but in D. sargus, a change in lipid composition was observed. These results suggest that P. erythrinus appears to be more impacted by food quality (different saturated and unsaturated FAs) than D. sargus, owing to a more restrictive diet. We hypothesize that the observed differences between inside and outside the MPA are not only related to the degree of protection, but also to the feeding preferences and behaviour of both fishes.Versión del editor0,000

ILC Reference Design Report Volume 4 - Detectors

This report, Volume IV of the International Linear Collider Reference Design Report, describes the detectors which will record and measure the charged and neutral particles produced in the ILC's high energy e+e- collisions. The physics of the ILC, and the environment of the machine-detector interface, pose new challenges for detector design. Several conceptual designs for the detector promise the needed performance, and ongoing detector R&D is addressing the outstanding technological issues. Two such detectors, operating in push-pull mode, perfectly instrument the ILC interaction region, and access the full potential of ILC physics.This report, Volume IV of the International Linear Collider Reference Design Report, describes the detectors which will record and measure the charged and neutral particles produced in the ILC's high energy e+e- collisions. The physics of the ILC, and the environment of the machine-detector interface, pose new challenges for detector design. Several conceptual designs for the detector promise the needed performance, and ongoing detector R&D is addressing the outstanding technological issues. Two such detectors, operating in push-pull mode, perfectly instrument the ILC interaction region, and access the full potential of ILC physics