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

Homeostatic NF-κB Signaling in Steady-State Migratory Dendritic Cells Regulates Immune Homeostasis and Tolerance

SummaryMigratory non-lymphoid tissue dendritic cells (NLT-DCs) transport antigens to lymph nodes (LNs) and are required for protective immune responses in the context of inflammation and to promote tolerance to self-antigens in steady-state. However, the molecular mechanisms that elicit steady-state NLT-DC maturation and migration are unknown. By comparing the transcriptome of NLT-DCs in the skin with their migratory counterparts in draining LNs, we have identified a novel NF-κB-regulated gene network specific to migratory DCs. We show that targeted deletion of IKKβ in DCs, a major activator of NF-κB, prevents NLT-DC accumulation in LNs and compromises regulatory T cell conversion in vivo. This was associated with impaired tolerance and autoimmunity. NF-κB is generally considered the prototypical pro-inflammatory transcription factor, but this study describes a role for NF-κB signaling in DCs for immune homeostasis and tolerance that could have implications in autoimmune diseases and immunity

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..

Functional CD169 on Macrophages Mediates Interaction with Dendritic Cells for CD8+ T Cell Cross-Priming

Splenic CD169+ macrophages are located in the marginal zone to efficiently capture blood-borne pathogens. Here, we investigate the requirements for the induction of CD8+ T cell responses by antigens (Ags) bound by CD169+ macrophages. Upon Ag targeting to CD169+ macrophages, we show that BATF3-dependent CD8α+ dendritic cells (DCs) are crucial for DNGR-1-mediated cross-priming of CD8+ T cell responses. In addition, we demonstrate that CD169, a sialic acid binding lectin involved in cell-cell contact, preferentially binds to CD8α+ DCs and that Ag transfer to CD8α+ DCs and subsequent T cell activation is dependent on the sialic acid-binding capacity of CD169. Finally, functional CD169 mediates optimal CD8+ T cell responses to modified vaccinia Ankara virus infection. Together, these data indicate that the collaboration of CD169+ macrophages and CD8α+ DCs for the initiation of effective CD8+ T cell responses is facilitated by binding of CD169 to sialic acid containing ligands on CD8α+ DCs

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

Leukocyte population dynamics and detection of IL-9 as a major cytokine at the mouse fetal-maternal interface.

International audienceDespite much interest in the mechanisms regulating fetal-maternal interactions, information on leukocyte populations and major cytokines present in uterus and placenta remains fragmentary. This report presents a detailed and quantitative study of leukocyte populations at the mouse fetal-maternal interface, including a comparison between pregnancies from syngeneic and allogeneic crosses. Our results provide evidence for drastic differences not only in the composition of leukocyte populations in the uterus during pregnancy, but also between uterine and placental tissues. Interestingly, we have observed a significant decrease in the number of myeloid Gr1+ cells including monocytes, and myeloid CD11c+ cells including DCs in placenta from an allogeneic pregnancy. In addition, we have compared the expression levels of a panel of cytokines in non-pregnant (NP) or pregnant mouse uterus, in placenta, or in their isolated resident leukocytes. Qualitative and quantitative differences have emerged between NP, pregnant uterus and placenta. Unexpectedly, IL-9 was the major cytokine in NP uterus, and was maintained at high levels during pregnancy both in uterus and placenta. Moreover, we have found that pregnancy is associated with an increase in uterine IL-1a and a significant decrease in uterine G-CSF and GM-CSF. Comparing allogeneic versus syngeneic pregnancy, less allogeneic placental pro-inflammatory cytokines CCL2 (MCP-1), CXCL10 (IP-10) and more IL1-α in whole uterus was reproducibly observed. To our knowledge, this is the first report showing a detailed overview of the leukocyte and cytokine repertoire in the uterus of virgin females and at the fetal-maternal interface, including a comparison between syngeneic and allogeneic pregnancy. This is also the first evidence for the presence of IL-9 in NP uterus and at the maternal-fetal interface, suggesting a major role in the regulation of local inflammatory or immune responses potentially detrimental to the conceptus

Antibody and dilutions used for flow cytometry staining.

<p>NA: not applicable.</p><p>Antibody and dilutions used for flow cytometry staining.</p

Cytokine and chemokine expression levels in placentae from syngeneic or allogeneic pregnancies (day 16.5 <i>pc</i>).

<p>Analyses were performed on the placentas from the same pregnant mice as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107267#pone-0107267-g008" target="_blank">Figure 8</a>. Proteins were measured from whole placenta (A), or from enriched placental leukocytes (B) from syngeneic or allogeneic pregnancies (note the important scale variations). Grey bars: syngeneic pregnancy, black bars: allogeneic pregnancy. Data are from 4 to 5 different samples. (*) p≤0.05, (**) p≤0.005, (***) p≤0.001.</p

Analyses of immune cell populations present in the uterus of NP or pregnant mice, and in placenta (16.5 d<i>pc</i>).

<p>Only viable cells excluding propidium iodide were analysed. Enriched leukocytes from NP (A,B) or pregnant (16.5 d<i>pc</i>) uterus (C,D) and placenta (E,F) were analysed by flow cytometry. R2-gated cells (left, cf. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107267#pone-0107267-g002" target="_blank">Figure 2</a>) were analysed on the basis of the following cell surface markers: TCRβ⁺/CD4⁺ (CD4 T cells); TCRβ⁺/CD8⁺ (CD8 T cells); NK1.1⁺/TCRβ⁻ (NK cells); TCRβ⁺/NK1.1⁺ (NKT cells); CD19⁺/B220⁺ (B cells); Gr1⁺/CD11b⁺ (myeloid Gr1+ cells including monocytes); Gr1^−/CD11c⁺/CD11b^Hi/low (myeloid CD11c+ cells including DCs). R1-gated cells (right, cf. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107267#pone-0107267-g002" target="_blank">Figure 2</a>) were analysed on the basis of the following cell surface markers: Gr1⁺/CD11b⁺ (Granulocytes); CD11b^Hi/Gr1⁺/Gr1^+/−/CD11c^+/− (Highly granulosity cells or HGC). The results are representative from a typical experiment of a pool of 7 mice (A, B) or from a single mouse (C, D, E, F). The experiment was repeated at least twice with 3–6 animals per assay.</p

Quantification of uterine and placental cytokines and chemokines in syngeneic pregnancy (day 16.5 <i>pc</i>).

<p>Uterine and placental tissues were prepared as described in Materials and Methods : (A) Uteri from NP mice, (B) Uteri from <b>syngeneic</b> pregnancy (day 16.5 d<i>pc</i>), (C) Placenta from <b>syngeneic</b> pregnancy (same animals). Samples were analyzed simultaneously for the following 22 cytokines: IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-9, IL-10, IL-12(p70), IL-13, IL-15, IL-17, CSF2 (GM-CSF), CSF3 (G-CSF), IFNγ, CXCL10 (IP-10), CXCL1 (KC), CCL2 (MCP-1), CCL3 (MIP-1α), CCL5 (RANTES), TNF-α. Only IL-9, IL-10, GM-CSF (CSF2), G-CSF (CSF3), CXCL10 (IP-10), IL-1α, CCL3 (MIP-1α), CXCL1 (KC), CCL2 (MCP-1) yielded reproducibly significant measurements and have been presented. Striped bars: whole organ, black bars: enriched leukocytes from the same organ. Data are from 4 to 5 different samples. Statistically significant differences: (*) p≤0.05, (***) p≤0.001.</p