β-Catenin Signaling Drives Differentiation and Proinflammatory Function of IRF8-Dependent Dendritic Cells.

β-Catenin signaling has recently been tied to the emergence of tolerogenic dendritic cells (DCs). In this article, we demonstrate a novel role for β-catenin in directing DC subset development through IFN regulatory factor 8 (IRF8) activation. We found that splenic DC precursors express β-catenin, and DCs from mice with CD11c-specific constitutive β-catenin activation upregulated IRF8 through targeting of the Irf8 promoter, leading to in vivo expansion of IRF8-dependent CD8α(+), plasmacytoid, and CD103(+)CD11b(-) DCs. β-Catenin-stabilized CD8α(+) DCs secreted elevated IL-12 upon in vitro microbial stimulation, and pharmacological β-catenin inhibition blocked this response in wild-type cells. Upon infections with Toxoplasma gondii and vaccinia virus, mice with stabilized DC β-catenin displayed abnormally high Th1 and CD8(+) T lymphocyte responses, respectively. Collectively, these results reveal a novel and unexpected function for β-catenin in programming DC differentiation toward subsets that orchestrate proinflammatory immunity to infection

The Philippeion at Olympia: The True Image of Philip?

The aim of this thesis has been to consider how Philip II of Macedonia presented himself to the Greek peoples after the Battle of Chaeronea in 336 BC. It examines the context and program of the Philippeion at Olympia in order to determine how Philip II negotiated his royal status in response to Greek opinion. This study takes into account the traditional role of the Macedonian kings, how they typically portrayed themselves, and to what purpose. It also explores Philip's propaganda specifically and the differing responses of various Greek peoples. Although Philip's role as Hegemon of the League of Corinth seems to be at odds with the Philippeion's classification as a victory monument and a display of the king's authority, further examination reveals that the Philippeion conforms with Philip's program of propaganda. It's message is also adaptable to the various perceptions of the Greek peoples as well as any Macedonian viewers. Master of Arts (MA

Oral and nasal mucosal pathways of prion infection in chronic wasting disease

2010 Fall.Includes bibliographical references.Chronic wasting disease (CWD) is a fatal neurodegenerative prion disease of deer, elk, and moose. The unique feature of CWD as a prion disease is its efficient transmission among cervids in nature. As with other prion infections, CWD disease inception relies on the conversion of the normal host cellular prion protein (PrPC) to the abnormal, protease-resistant isoform (PrPCWD)--the diagnostic hallmark of prion diseases. Since its detection in Colorado in 1967, CWD has spread to captive and free-ranging cervid species in 16 additional states, 3 Canadian provinces, and one Asian country. CWD is also exceptional as the only prion disease to afflict a free-ranging, wildlife population. Understanding the facile means by which CWD is transmitted from animal to animal is important not only in understanding prion transmission overall but also in elucidating the potential public health consequences of cross species prion transmission. This dissertation work asks whether and how CWD prions are able to cross the oral and nasal mucosa to induce infection and disease. The above questions were addressed through the use of two strains of transgenic mice that express the normal cervid prion protein [Tg(CerPrP)1536, Tg(CerPrP-E226)5037+/-] and prion protein knockout mice [FVB PrP0/0] exposed by either aerosol, nasal, or oral route to CWD prions. In the first series of studies, cohorts of Tg(CerPrP)1536 mice were exposed to brain homogenates from either CWD-infected or CWD-naïve deer via either aerosolization or direct nasal installation. In the second series of studies, cohorts of Tg(CerPrP-E226)5037+/- mice were exposed to the same inocula via installation onto the lingual mucosal surface which had or had not been previously subjected to superficial abrasions. Mice were then observed and tissues from each cohort, at time points ranging from weeks to as long as 2 years post inoculation, were examined for the presence of the abnormal prion protein of CWD (PrPCWD) using western blotting and immunohistochemistry assays. The final studies employed the same inoculation techniques used in the first two studies to seek to identify early (less than 4 hours) sites of prion entry via the mucous membranes. The results of these dissertation studies demonstrated; 1) that CWD could be transmitted by aerosol exposure with high efficiency compared with direct inoculation onto the nasal mucosa; and 2) that micro-abrasions to the lingual surface greatly facilitated CWD prion transmission. Finally and perhaps surprisingly, we were unable to detect PrPCWD in either the nasal or oral mucosa shortly after inoculation or at any time, even after the onset of clinical symptoms of CWD. The results from these studies suggest that; 1) CWD prions can be transmitted by aerosol exposure; thus exposure to the respiratory system merits increased consideration in prion transmission and biosafety; 2) minor oral mucosal injury does greatly facilitate prion infection--a potentially significant co-factor in CWD transmission of foraging cervids; and 3) these mucosal pathways may explain how and why CWD is transmitted with high efficiency in animals exposed to low concentrations of prions in nature

Toll-Like Receptor Initiated Host Defense against Toxoplasma gondii

Toxoplasma gondii is an intracellular pathogen notable for its ability to establish a stable host-parasite relationship amongst a wide range of host species and in a large percentage of the human population. Toll-like receptor signaling through MyD88 is a critical pathway in initiating defense against this opportunistic protozoan and may also be a mediator of pathology during immune dysfunction. Other MyD88 independent signaling pathways are also involved in the host-parasite interaction. These responses can be triggered by the parasite itself, but interactions with the intestinal microbiota add additional complexity during enteric infection

Peptidyl-prolyl cis-trans isomerases (immunophilins) and their roles in parasite biochemistry, host-parasite interaction and antiparasitic drug action.

Immunophilin is the collective name given to the cyclophilin and FK506-binding protein (FKBP) families. As the name suggests, these include the major binding proteins of certain immunosuppressive drugs: cyclophilins for the cyclic peptide cyclosporin A and FKBPs for the macrolactones FK506 and rapamycin. Both families, although dissimilar in sequence, possess peptidyl-prolyl <i>cis-trans</i> isomerase activity in vitro and can play roles in protein folding and transport, RNA splicing and the regulation of multiprotein complexes in cells. In addition to enzymic activity, many immunophilins act as molecular chaperones. This property may be conferred by the isomerase domain and/or by additional domains. Recent years have seen a great increase in the number of known immunophilin genes in parasitic protozoa and helminths and in many cases their products have been characterized biochemically and their temporal and spatial expression patterns have been examined. Some of these genes represent novel types: one example is a <i>Toxoplasma gondii</i> gene encoding a protein with both cyclophilin and FKBP domains. Likely roles in protein folding and oligomerisation, RNA splicing and sexual differentiation have been suggested for parasite immunophilins. In addition, unexpected roles in parasite virulence (Mip FKBP of <i>Trypanosoma cruzi</i>) and host immuno-modulation (e.g. 18-kDa cyclophilin of <i>Toxoplasma gondii</i>) have been established. Furthermore, in view of the potent antiparasitic activities of cyclosporins, macrolactones and nonimmunosuppressive derivatives of these compounds, immunophilins may mediate drug action and/or may themselves represent potential drug targets. Investigation of the mechanisms of action of these agents may lead to the design of potent and selective antimalarial and other antiparasitic drugs. This review discusses the properties of immunophilins in parasites and the 'animal model' <i>Caenorhabditis elegans</i> and relates these to our understanding of the roles of these proteins in cellular biochemistry, host-parasite interaction and the antiparasitic mechanisms of the drugs that bind to them

Vaccines against toxoplasma gondii : challenges and opportunities

Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge

Toxoplasma gondii Inhibits Covalent Modification of Histone H3 at the IL-10 Promoter in Infected Macrophages

Infection of macrophages with the protozoan parasite Toxoplasma gondii results in inhibition of a large panel of LPS-responsive cytokines, including TNF-α, while leaving others such as IL-10 intact. Recent studies provide evidence that the parasite interferes with chromatin remodeling at the TNF-α promoter that is normally associated with LPS stimulation, but that is not required for TLR4 induction of IL-10. Here, we examined the effect of Toxoplasma on IL-10 induced by simultaneous signaling through TLR4 and FcγR, a combined stimulus that triggers histone H3 covalent modification at the IL-10 promoter resulting in high level IL-10 cytokine production. We show that the parasite inhibits high level IL-10 production and prevents histone H3 Ser10 phosphorylation and Lys9/14 acetylation at the IL-10 promoter. These results provide compelling evidence that T. gondii targets the host cell chromatin remodeling machinery to down-regulate cytokine responses in infected macrophages

Kinetoplastids:related protozoan pathogens, different diseases

Kinetoplastids are a group of flagellated protozoans that include the species Trypanosoma and Leishmania, which are human pathogens with devastating health and economic effects. The sequencing of the genomes of some of these species has highlighted their genetic relatedness and underlined differences in the diseases that they cause. As we discuss in this Review, steady progress using a combination of molecular, genetic, immunologic, and clinical approaches has substantially increased understanding of these pathogens and important aspects of the diseases that they cause. Consequently, the paths for developing additional measures to control these “neglected diseases” are becoming increasingly clear, and we believe that the opportunities for developing the drugs, diagnostics, vaccines, and other tools necessary to expand the armamentarium to combat these diseases have never been better

Immunization with a DNA vaccine cocktail encoding TgPF, TgROP16, TgROP18, TgMIC6, and TgCDPK3 genes protects mice against chronic toxoplasmosis

Toxoplasmosis is a zoonotic disease caused by the intracellular protozoan Toxoplasma gondii; and a major source of infection in humans is via ingestion of T. gondii tissue cysts. Ultimately, the goal of anti-toxoplasmosis vaccines is to elicit a sustainable immune response, capable of preventing formation of the parasite tissue cysts—or, at least, to restrain its growth. In this study, we formulated a cocktail DNA vaccine and investigated its immunologic efficacy as a protection against the establishment of T. gondii cysts in the mouse brain. This multicomponent DNA vaccine, encoded the TgPF, TgROP16, TgROP18, TgMIC6, and TgCDPK3 genes, which play key roles in the pathogenesis of T. gondii infection. Results showed that mice immunized via intramuscular injection three times, at 2-week intervals with this multicomponent DNA vaccine, mounted a strong humoral and cellular immune response, indicated by significantly high levels of total IgG, CD4+ and CD8+ T lymphocytes, and antigen-specific lymphocyte proliferation when compared with non-immunized mice. Immunization also induced a mixed Th1/Th2 response, with a slightly elevated IgG2a to IgG1 ratio. The increased production of proinflammatory cytokines gamma-interferon, interleukin-2, and interleukin-12 (p 0.05). The number of brain cysts in immunized mice was significantly less than those in non-immunized mice (643.33 ± 89.63 versus 3,244.33 ± 96.42, p < 0.0001), resulting in an 80.22% reduction in the parasite cyst burden. These findings indicate that a multicomponent DNA vaccine, encoding TgPF, TgROP16, TgROP18, TgMIC6, and TgCDPK3 genes, shows promise as an immunization strategy against chronic toxoplasmosis in mice, and calls for a further evaluation in food-producing animals

Why Dutch officials take bribes:A toxic mix of factors

The aim of this study was to gain an in-depth understanding of the factors that underlie public officials’ engagement in corruption. Given the significant public interest, we gained permission from the Dutch Ministry of Justice to analyze multiple confidential criminal files of cases in which Dutch public officials took bribes from private companies. Extending previous research, we analyzed three types of factors, individual factors, organizational factors, and factors related to the relationships between corrupt officials and their bribers. Moreover, for the first time, we considered the interplay between these three types of factors. The results suggest that public officials’ engagement in bribery is rooted in a combination of individual, organizational and relationship variables that influence and reinforce each other, creating a toxic mix. This implies that the battle against bribery can be fought on multiple fronts, whereby changing one critical factor may cause the mix to lose its toxicity