Penicillin kills chlamydia following the fusion of bacteria with Lysosomes and prevents genital inflammatory lesions in C. muridarum-infected mice

The obligate intracellular bacterium Chlamydia exists as two distinct forms. Elementary bodies (EBs) are infectious and extra-cellular, whereas reticulate bodies (RBs) replicate within a specialized intracellular compartment termed an ‘inclusion’. Alternative persistent intra-cellular forms can be induced in culture by diverse stimuli such as IFNγ or adenosine/EHNA. They do not grow or divide but revive upon withdrawal of the stimulus and are implicated in several widespread human diseases through ill-defined in vivo mechanisms. β-lactam antibiotics have also been claimed to induce persistence in vitro. The present report shows that upon penicillin G (pG) treatment, inclusions grow as fast as those in infected control cells. After removal of pG, Chlamydia do not revert to RBs. These effects are independent of host cell type, serovar, biovar and species of Chlamydia. Time-course experiments demonstrated that only RBs were susceptible to pG. pG-treated bacteria lost their control over host cell apoptotic pathways and no longer expressed pre-16S rRNA, in contrast to persistent bacteria induced with adenosine/EHNA. Confocal and live-video microscopy showed that bacteria within the inclusion fused with lysosomal compartments in pG-treated cells. That leads to recruitment of cathepsin D as early as 3 h post pG treatment, an event preceding bacterial death by several hours. These data demonstrate that pG treatment of cultured cells infected with Chlamydia results in the degradation of the bacteria. In addition we show that pG is significantly more efficient than doxycycline at preventing genital inflammatory lesions in C. muridarum-C57Bl/6 infected mice. These in vivo results support the physiological relevance of our findings and their potential therapeutic applications

Claudine Drame, Des films pour le dire, reflets de la Shoah au cinéma 1945-1985

L’année 2007 a été marquée par la sortie de deux ouvrages relatifs à la représentation au cinéma du génocide des Juifs d’Europe : celui de Claudine Drame et Le cinéma et la Shoah, un art à l’épreuve de la tragédie du XXe siècle, coordonné par Jean-Michel Frodon aux éditions Cahiers du Cinéma. Ces deux livres partent du même principe : jeter un regard rétrospectif sur des dizaines d’années de représentation des crimes génocidaires nazis au cinéma, en concluant sur la suprématie du film Shoah d..

I kappa B kinase alpha (IKKα) activity is required for functional maturation of dendritic cells and acquired immunity to infection

Dendritic cells (DC) are required for priming antigen-specific T cells and acquired immunity to many important human pathogens, including Mycobacteriuim tuberculosis (TB) and influenza. However, inappropriate priming of auto-reactive T cells is linked with autoimmune disease. Understanding the molecular mechanisms that regulate the priming and activation of naïve T cells is critical for development of new improved vaccines and understanding the pathogenesis of autoimmune diseases. The serine/threonine kinase IKKα (CHUK) has previously been shown to have anti-inflammatory activity and inhibit innate immunity. Here, we show that IKKα is required in DC for priming antigen-specific T cells and acquired immunity to the human pathogen Listeria monocytogenes. We describe a new role for IKKα in regulation of IRF3 activity and the functional maturation of DC. This presents a unique role for IKKα in dampening inflammation while simultaneously promoting adaptive immunity that could have important implications for the development of new vaccine adjuvants and treatment of autoimmune diseases

Soluble ectodomain CD163 and extracellular vesicle-associated CD163 are two differently regulated forms of 'soluble CD163' in plasma

CD163 is the macrophage receptor for uptake of hemoglobin-haptoglobin complexes. The human receptor can be shed from the macrophage surface owing to a cleavage site for the inflammationinducible TACE/ADAM17 enzyme. Accordingly, plasma `soluble CD163' (sCD163) has become a biomarker for macrophage activity and inflammation. The present study disclosed that 10% of sCD163 in healthy persons is actually extracellular vesicle (EV)-associated CD163 not being cleaved and shed. Endotoxin injection of human volunteers caused a selective increase in the ectodomain CD163, while septic patients exhibited high levels of both soluble ectodomain CD163 and extracellular vesicle (EV) CD163, the latter representing up 60% of total plasma CD163. A poor prognosis of septic patients measured as the sequential organ failure assessment (SOFA) score correlated with the increase in membrane-associated CD163. Our results show that soluble ectodomain CD163 and EV CD163 in plasma are part of separate macrophage response in the context of systemic inflammation. While that soluble ectodomain CD163 is released during the acute systemic inflammatory response, this is not the case for EV CD163 that instead may be released during a later phase of the inflammatory response. A separate measurement of the two forms of CD163 constituting `soluble CD163' in plasma may therefore add to the diagnostic and prognostic value

Receptor Activator of NF-κB Orchestrates Activation of Antiviral Memory CD8 T Cells in the Spleen Marginal Zone

The spleen plays an important role in protective immunity to bloodborne pathogens. Macrophages and dendritic cells (DCs) in the spleen marginal zone capture microbial antigens to trigger adaptive immune responses. Marginal zone macrophages (MZMs) can also act as a replicative niche for intracellular pathogens, providing a platform for mounting the immune response. Here, we describe a role for RANK in the coordinated function of antigen-presenting cells in the spleen marginal zone and triggering anti-viral immunity. Targeted deletion of RANK results in the selective loss of CD169+ MZMs, which provide a niche for viral replication, while RANK signaling in DCs promotes the recruitment and activation of anti-viral memory CD8 T cells. These studies reveal a role for the RANKL/RANK signaling axis in the orchestration of protective immune responses in the spleen marginal zone that has important implications for the host response to viral infection and induction of acquired immunity. Habbeddine et al. show that RANK signaling in the spleen marginal zone plays an important role in orchestrating protective immune responses to viral infection. They show that RANK expressed by macrophages supports viral replication, while RANK signaling in dendritic cells promotes the recruitment and activation of memory CD8 T cells

pG induces lysosome entry into bacterial inclusions.

<p>HeLa cells were infected by <i>C. trachomatis</i> serovar L2 and treated with pG at 3 hpi or left untreated. At 24 hpi, cells were either fixed and stained (A and B) or readily observed (C and D). Scale bar: 10 μm. The experiments have been repeated at least 3 times. <b>A-</b> Staining of pG-treated and untreated infected cells as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083511#pone-0083511-g001" target="_blank">Figure 1</a>, adding anti-Cathepsin D labelling (red). <b>B-</b> Staining of pG-treated and untreated infected cells using 5 µM BODIPY-pepstatin-FL (green) and Hoechst (blue). <b>C-</b> Cells were incubated with lysotracker for 30 min at 37°C before observation. Lysotracker localizes mainly in inclusions in pG-treated infected cells. Details show strong bright spots in these inclusions, suggesting a lysosome entry. Arrowhead: inclusion, arrow: bright spot. DIC: differential interference contrast. <b>D-</b> Time lapse using a confocal microscope with high resonance scanner. In grey, differential interference contrast, in red, lysotracker. A lysosome (white arrow) enters and stays inside an inclusion in pG-treated infected cells.</p

In the presence of pG, the recruitment of lysosomes precedes the death of <i>Chlamydia trachomatis</i>.

<p>HeLa cells were infected by <i>C. trachomatis</i> serovar L2. At 15 hpi, cells were treated or not with pG for 3 h (18 hpi), 6 h (21 hpi), 15 h (30 hpi), or 24 h (39 hpi). <b>A-</b> Cells were either fixed and stained as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083511#pone-0083511-g004" target="_blank">Figure 4</a> or <b>B-</b> processed to measure pre-16S and GAPDH RNA expression, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083511#pone-0083511-g003" target="_blank">Figure 3</a>. The experiments have been repeated 3 times.</p

pG restores apoptotic pathways in the host cells and inhibits RNA biosynthesis of <i>Chlamydia</i>.

<p><b>A-</b> HeLa cells were infected by <i>C. trachomatis</i> serovar L2 and treated with pG at 2 hpi or left untreated. At 21 hpi, STS was added to the culture medium. Cells were fixed at 48 hpi and stained as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083511#pone-0083511-g001" target="_blank">Figure 1</a>. Scale bar: 10 μm. Left panel: data representation from the pictures after calculation of the percentages of apoptotic infected cells. Right panel: Infected-HeLa cells were treated with pG at either 2 hpi or 29 hpi or left untreated. Then, STS was added at 31 hpi. Cells were fixed at 39 hpi and percentages of apoptotic infected cells were determined and presented as in the left panel. <b>B-</b> HeLa cells were infected by <i>C. trachomatis</i> serovar L2 and treated at 1 hpi with either pG or Ad/EHNA, or left untreated. In some experimental conditions (<b>R</b>), pG or Ad/EHNA were removed from culture medium at 32 hpi and the culture was continued for 43 h. At 75 hpi, cells were processed to measure pre-16S and GAPDH RNA expression. The experiments have been repeated 3 times. * correspond to p<i><</i> 0.05.</p

Penicillin G (pG) treatment <i>in vitro</i> does not induce classical persistence of <i>C. trachomatis</i>.

<p>HeLa cells infected by <i>C. trachomatis</i> serovar L2 were treated at 3 hpi with either pG (100 IU/mL) or Ad/EHNA, or left untreated. <b>A-</b> At different times after infection, cells were fixed and stained using an anti-<i>chlamydia</i> antibody (green) and Hoechst (blue). Scale bar: 10 µm. <b>B-</b> pG or Ad/EHNA were removed at 32 hpi from culture medium and culture was continued for 43 h. At 75 hpi, cells were processed for the titration of recovered infectious activity. <b>C-</b> HeLa cells infected by <i>C. trachomatis</i> serovar L2 were treated at 3 hpi either with 1, 10 or 100 IU/mL pG or left untreated. In some samples (+), pG was removed at 24 hpi from culture medium and culture was continued. At 48 hpi or 100 hpi, cell layers (left panel) and supernatants (right panel) were processed for the titration of recovered infectious activity. All experiments have been repeated at least 3 times. * correspond to p<i><</i> 0.05, ** correspond to p <0.01, *** correspond to p < 0.001. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083511#pone.0083511.s001" target="_blank">Figure S1</a></p

The role of the immune system beyond the fight against infection

The immune system was identified as a protective factor during infectious diseases over a century ago. Current definitions and textbook information are still largely influenced by these early observations, and the immune system is commonly presented as a defence machinery. However, host defence is only one manifestation of the immune system’s overall function in the maintenance of tissue homeostasis and system integrity. In fact, the immune system is integral part of fundamental physiological processes such as development, reproduction and wound healing, and a close crosstalk between the immune system and other body systems such as metabolism, the central nervous system and the cardiovascular system is evident. Research and medical professionals in an expanding range of areas start to recognise the implications of the immune system in their respective fields. This chapter provides a brief historical perspective on how our understanding of the immune system has evolved from a defence system to an overarching surveillance machinery to maintain tissue integrity. Current perspectives on the non-defence functions of classical immune cells and factors will also be discusse