Inbred mouse strains exhibit differences in susceptibility to influenza A infections. However, the molecular mechanisms underlying these differences are unknown. Therefore, we infected a highly susceptible mouse strain (DBA/2J) and a resistant strain (C57BL/6J) with influenza A H1N1 (PR8) and performed genome-wide expression analysis. We found genes expressed in lung epithelium that were specifically down-regulated in DBA/2J mice, whereas a cluster of genes on chromosome 3 was only down-regulated in C57BL/6J. In both mouse strains, chemokines, cytokines and interferon response genes were up-regulated, indicating that the main innate immune defense pathways were activated. However, many immune response genes were up-regulated in DBA/2J much stronger than in C57BL/6J, and several immune response genes were exclusively regulated in DBA/2J. Thus, susceptible DBA/2J mice showed a hyper-inflammatory response. This response is similar to infections with highly pathogenic influenza virus and may serve as a paradigm for a hyper-inflammatory host response to influenza A virus.

BACKGROUND: Several facultative anaerobic bacteria with potential therapeutic abilities are known to preferentially colonize solid tumors after systemic administration. How they efficiently find and invade the tumors is still unclear. However, this is an important issue to be clarified when bacteria should be tailored for application in cancer therapy. METHODOLOGY/PRINCIPAL FINDINGS: We describe the initial events of colonization of an ectopic transplantable tumor by Salmonella enterica serovar Typhimurium. Initially, after intravenous administration, bacteria were found in blood, spleen, and liver. Low numbers were also detected in tumors associated with blood vessels as could be observed by immunohistochemistry. A rapid increase of TNF-alpha in blood was observed at that time, in addition to other pro-inflammatory cytokines. This induced a tremendous influx of blood into the tumors by vascular disruption that could be visualized in H&E stainings and quantified by hemoglobin measurements of tumor homogenate. Most likely, together with the blood, bacteria were flushed into the tumor. In addition, blood influx was followed by necrosis formation, bacterial growth, and infiltration of neutrophilic granulocytes. Depletion of TNF-alpha retarded blood influx and delayed bacterial tumor-colonization. CONCLUSION: Our findings emphasize similarities between Gram-negative tumor-colonizing bacteria and tumor vascular disrupting agents and show the involvement of TNF-alpha in the initial phase of tumor-colonization by bacteria.

Abstract Recent evidence suggests that regulatory pathways might control sustained high levels of FOXP3 in regulatory CD4(+)CD25(hi) T (T(reg)) cells. Based on transcriptional profiling of ex vivo activated T(reg) and helper CD4(+)CD25(-) T (T(h)) cells we have identified GARP (glycoprotein-A repetitions predominant), LGALS3 (lectin, galactoside-binding, soluble, 3) and LGMN (legumain) as novel genes implicated in human T(reg) cell function, which are induced upon T cell receptor stimulation. Retroviral over-expression of GARP in antigen-specific T(h) cells leads to an efficient and stable re-programming of an effector T cell towards a regulatory T cell, which involves up-regulation of FOXP3, LGALS3, LGMN, and other T(reg)-associated markers. In contrast, over-expression of LGALS3 and LGMN enhance FOXP3 and GARP expression, but only partially induced a regulatory phenotype. Lentiviral down-regulation of GARP in T(reg) cells significantly impaired the suppressor function and was associated with down-regulation of FOXP3. Moreover, down-regulation of FOXP3 resulted in similar phenotypic changes and down-regulation of GARP. This provides compelling evidence for a GARP-FOXP3 positive feedback loop and provides a rational molecular basis for the known difference between natural and TGF-beta induced T(reg) cells as we show here that the latter do not up-regulate GARP. In summary, we have identified GARP as a key receptor controlling FOXP3 in T(reg) cells following T cell activation in a positive feedback loop assisted by LGALS3 and LGMN, which represents a promising new system for the therapeutic manipulation of T cells in human disease.

Murine B1 cells have been shown to be able to switch to IgA in vitro. In agreement, we could demonstrate in the peritoneum of mice the presence of IgA producing B1 cells. Interestingly, enzyme-linked immunospot assays of lipopolysaccharide stimulated cultures revealed that only the B1b cell subpopulation contained high numbers of such cells while IgA producing B cells were rare amongst the B2 and B1a cell populations. This was confirmed by RT-PCR on sorted peritoneal B cell subpopulations. In addition, the variable regions associated with IgA of peritoneal B1b cells displayed extensive variation due to somatic hypermutation. In contrast, mutations were found only at low frequencies in VH regions associated with IgM of both B1 cell populations. Thus, peritoneal B1b cells display many similarities to B2 cells. This finding is consistent with the idea of a layered immune system in which peritoneal B1a and splenic follicular B2 cells appear at the two extremes and peritoneal B1b and B2 cells represent intermediates.

OBJECTIVES: This study evaluates the prevalence of alexithymia in multiple sclerosis and examines the links between alexithymia, depression and anxiety. METHOD: Sixty-one subjects aged between 18 and 60 years and suffering from multiple sclerosis took part in the study. The psychological assessment consisted of an interview with a psychologist and three questionnaires: the Toronto Alexithymia Scale (TAS), the State-Trait Anxiety Inventory (STAI), the Beck Depression Inventory (BDI). RESULTS: The prevalence of alexithymia was 42.5%, 34.4% for depression and 44.3% for anxiety (high and moderate level). The alexithymic subjects were more depressed and anxious. Results indicated positive correlations between anxiety (state and trait), depression and alexithymia scores. The various dimensions of alexithymia were found to be diversely correlated with anxiety and depression. CONCLUSIONS: Our results point out the importance of anxiety in multiple sclerosis and the specificity of alexithymia.

Listeriolysin O (LLO), the pore-forming toxin of L. monocytogenes (L.m.), is a prototype of the cholesterol dependent cytolysins (CDCs) secreted by several pathogenic and non-pathogenic Gram-positive bacteria. In addition to mediating escape of the bacterium into the cytosol, this toxin is generally believed to be a central player in host-pathogen interactions during L.m. infection. LLO triggers influx of Ca(2+) into host cells as well as release from intracellular stores. Thus, many of the cellular responses induced by LLO are related to calcium signalling. Interestingly, in this study, we report that prolonged exposure to LLO desensitizes cells to Ca(2+) mobilization upon subsequent stimulations. Cells pre-exposed to LLO, L.m but not to the LLO deficient mutant L.mDeltahly were found to be highly refractory to Ca(2+) induction in response to receptor mediated stimulation. Such cells also exhibit diminished Ca(2+) signals in responses to LLO and thapsigargin. The presented results suggest that this phenomenon is due to depletion of intracellular Ca(2+) stores. The ability of LLO to desensitize immune cells provide a significant hint into the possible role played by CDCs in the evasion of the immune system by the respective bacterial pathogens.