Trace elements are essential for the host defence against infections, and during common infections, the balance of trace elements is changed in serum and tissues. Supplementation with selenium (Se), an essential trace element, is known to decrease the severity of coxsackievirus B3 (CVB3) infection in mice. Even the non-essential trace element arsenic (As) seems to influence the replication of some viruses. During the course of an acute CVB3 infection in mice, Se concentrations decreased in most tissues and were negatively correlated to viral load in our study. However, As concomitantly decreased in most tissues. As has previously been shown to interfere with the balance of essential trace elements. However, in the present study As supplementation in healthy mice resulted in minor effects on seven studied trace elements in serum and tissues. The effects of As supplementation were more pronounced in CVB3-infected mice, with an increase in As, but a decrease in Se in most tissues when compared with non-infected mice. As supplementation during CVB3 infection in mice decreased viral RNA concentrations in the brain (97%) and pancreas (75%), two of the target organs of this infection. In vitro experiments indicate that As caused an impaired virion assembly or release. In vivo, infection-induced expression of the host defence-associated genes nuclear factor κB (NFκB) and interferon γ (IFN-γ) were unaffected by As supplementation, except for an earlier increase in IFN-γ in the brain. In conclusion, a clinically relevant dose of As decreased the replication of CVB3 in vitro and in vivo. This antiviral effect in vivo was not related to changes in specific trace elements or in the host’s immune-mediated defence. Although the mechanism underlying the observed effect on viral replication remains to be further elucidated, As seems to be an intriguing trace element to study in the pursuit of new antiviral drugs.

Francisella tularensis is a gram-negative, highly virulent, intracellular bacterium which causes the zoonotic disease tularemia. The subspecies tularensis and holarctica are clinically important, and the former is the more virulent. The intracellular lifestyle of F. tularensis is not completely understood, but after uptake in monocytes, the bacterium escapes from the phagosome within hours and replicates massively in the cytosol. The escape is dependent on factors encoded by the Intracellular Growth Locus (igl) operon, located in the Francisella Pathogenicity Island, FPI. The thesis was aimed to clarify and understand the interaction of F. tularensis strains with the endosomal pathway of monocytic cells in general and the roles of the Igl proteins and the global regulator MglA for this interaction in particular. A focus has also been to elucidate the roles of reactive oxygen and nitrogen species for the intracellular host-parasite interaction. We show that mutants in the IglB, IglC, or IglD proteins or their regulator MglA of the live vaccine strain, LVS (subspecies holarctica), all demonstrated reduced replication rates and lowered cytopathogenicity compared to the wild type in a J774 mouse macrophage cell model. Colocalization with LAMP-1 was significantly increased for the IglC, IglD and MglA mutants compared to LVS. This indicated an impaired ability to escape into the cytoplasm, while at the same time they, like LVS, partly prevented fusion with lysosomes. IFN-γ activation of the J774 host cells prior to infection had a bactericidal effect on LVS and all of the mutants, though the cidal effect was significantly more pronounced for the mutants. Following IFN-γ activation, a majority of the mutant-containing phagosomesfused with lysosomeswhile LVS remained localized in the cytosol without significantly increased interactions with the endosomal pathway. Previous studies have revealed that IFN-γ activation of F. tularensis-infected macrophages leads to control of infection but conclusions about the importance of reactive nitrogen and oxygen species on bacterial killing are inconsistent. We found that the growth inhibition resulting from IFN-γ activation could not be attributed to an increased oxidative burst since PMA-induced superoxide production was still inhibited by LVS to the same extent as in non-activated macrophages. On the other hand, reactive nitrogen species may in part have contributed to the cidal effect. To further assess the role of reactive nitrogen species to the killing of F. tularensis, nitric oxide was administrated exogenously to J774 cells infected with LVS. This led to significant killing of intracellular LVS with a concomitant increased phagosomal localization and downregulation of the virulence gene regulator mglA. These effects were reversed by addition of a peroxynitrite decomposition catalyst. A spontaneous avirulent mutant of subspecies tularensis, strain FSC043, was previously demonstrated to provide protective immunity in mice. Here, microscopic analyses of the strain revealed an unusual intracellular localization with a delayed phagosomal escape. This may account for the low virulence, while at the same time FSC043 remains immunogenic and thereby confers protection. The igl operon is intact in strain FCS043 and we hypothesize that a defect in the FPI gene pdpC contributed to the observed phenotype. Altogether, this thesis work demonstrates the importance of the mglA and igl genes for the virulence of F. tularensis and specifically their important roles for a functional phagosomal escape and inhibition of the host cell oxidative burst. Also, addition of exogenous nitric oxide likely leads to formation of peroxynitrite intracellularly, a reactive molecule which confines the bacterium to the phagosome and confers a significant bactericidal effect on intracellular F. tularensis.

Influenza is a serious illness worldwide, causing high morbidity and mortality. 10-20% of world population fall ill with influenza each year and 250 000 - 500 000 people die annually. The most efficacious protection to date is vaccination. Current vaccines are efficient only one season because of fast mutation rate of influenza virus. The effort to create an effective vaccine faces lack of potent adjuvant, which can adequately stimulate and modulate immune system to protect organism from virus infection. Moreover, todays vaccines administered parenterally do not induce immune response on mucosal surfaces. Bacillus firmus, a Gram-positive non-pathogenic bacterium, has strong immmune-modulating properties and is able to induce cross-protection when administered with influenza virus antigens. Immunization with Bacillus firmus stimulates production of neutralizing antibodies, but other mechanisms of its action remain to be elucidated. To better understand the mechanisms how is antiviral immunity enhanced by Bacillus firmus (delipidated fraction, DBF), the effect of immunization with DBF only was studied on mouse model. In last decade it has become obvious that intranasal immunization can induce both systemic and mucosal immune response and in case of influenza it can induce cross-protection. Therefore...

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After kidney transplantation the recipient's immune system responds to the donor's antigens and the graft rejection occurs. Borderline changes are a frequent diagnosis after kidney transplantation, representing only mild rejection signs. Some patients with borderline changes undergo progression to rejection. The identification of these at- risk patients by biomarkers will allow enhanced treatment and help to prevent the development of rejection. The aim of my work was to verify biomarkers of rejection in patients with borderline changes. Chemokines CXCL9, CXCL10 and CCL17 in urine/serum of 40 patients with subclinical borderline changes at 3 months and in 25 patients with early borderline changes were determined by ELISA. At 3 months, the higher CXCL10 level predicted rejection with AUC=0.749, p=0.024. High levels of CXL10 had also been found in patients with BKV infection. We did not confirm the relationship between rejection and the CXCL9 and CCL17. In the early posttransplant period the levels of CXCL10 and CXCL9 were elevated in all patients and therefore couldn't be used to predict rejection. The alloreactivity was examined using IFN-γ ELISPOT (n=38). No association between the frequency of IFN-γ producing cells after stimulation with donor cells or CMV peptides and the development of...

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20084号 / 医博第4177号 / 新制||医||1018(附属図書館) / 33200 / 京都大学大学院医学研究科医学専攻 / (主査)教授 生田 宏一, 教授 山田 亮, 教授 椛島 健治 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

no / Interleukin-33 has recently gained much attention due to its role in allergic responses. It has been shown to amplify Th2 responses and to act as a damage-associated molecular pattern. IL-33 acts on a broad range of cells and has been proposed to link innate and adaptive features of allergic responses. It was the aim of this study to investigate this property of IL-33 in the inflammatory response characterising atopic dermatitis (AD). We have analysed the response of skin-resident cells derived from patients with AD and healthy donors with regard to the expression of IL-33 and its receptor ST2. The functional impact of IL-33 on CD4+ T cells was investigated. Keratinocytes and dermal fibroblasts clearly differ in their regulation of IL-33. In fibroblasts, the concerted action of TNF-α and IL-1β was the strongest inducer, whereas IFN-γ is clearly the key molecule that upregulates IL-33 in keratinocytes with a more pronounced response of cells derived from patients with AD. Keratinocytes from patients with AD showed a markedly higher constitutive expression level of surface ST2. CD4+ T cells respond to IL-33. Unexpectedly, IL-33 failed to induce a significant secretion of IL-5 or IL-13. By contrast, high amounts of IFN-γ were detectable if IL-33 was added to the T-cell receptor-stimulated cells or in combination with IL-12. These results suggest that IL-33 and IFN-γ are closely interlinked in epidermal AD inflammation. IFN-γ induces IL-33 in keratinocytes and IL-33 acts on activated T cells to further increase the release of IFN-γ, therefore contributing to drive skin inflammation towards chronic responses.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23796号 / 医博第4842号 / 新制||医||1058(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 森信 暁雄, 教授 椛島 健治, 教授 杉田 昌彦 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Eimerian parasites infect cattle worldwide. Information on the infection dynamics of these parasites is lacking in the central Appalachian region of the United States. Studies aimed at characterizing the seasonal dynamics of eimerian parasites in this region were carried out in order to assess the impact of these organisms in grazing systems. In these studies the prevalence of Eimeria spp. infection was highest in calves less than one year of age and subsequently decreased to stable levels in older animals. Although E. bovis was the most common species identified in calves, heifers and cows, mixed species infections dominated. Additional studies were carried out to investigate the effect of stress on Eimeria spp. infection in beef calves. Lower stress, two-stage, weaning methods had no effect on Eimeria spp. infection dynamics in beef calves. These findings must be interpreted in light of the fact that calves used in this study were not managed in a way typical of many calves in the U.S.A. The fact that they were only transported short distances, never commingled, or exposed to a livestock market may explain why a rise in post weaning FOC was not observed. A model of stress- induced coccidiosis was developed using dexamethasone and E. bovis challenge. In this model, an oral challenge of at least 500,000 sporulated E. bovis oocysts in addition to dexamethasone injection at 7 days post challenge increased subsequent FOC. Further investigation of the immune response to E. bovis challenge during times of stress indicates that stress-induced suppression of cell mediated immunity and E. bovis challenge are required to increase subsequent oocyst shedding. These findings may represent the mechanism associated with stress-induced outbreaks of coccidiosis reported to occur in beef cattle in the United States. / Ph. D.

Equine Protozoal Myeloencephalitis (EPM) is a serious neurologic disease of horses in the United States. The primary etiologic agent is Sarcocystis neurona (S. neurona). Currently, there is limited knowledge regarding the protective or pathologic immune response to infection to the intracellular protozoa S. neurona. The objective of these studies was to determine the effects of S. neurona infection on the immune response of horses that had EPM due to natural infection (experiment 1) and experimental infection (experiment 2). In experiment 1, twenty-two horses with naturally occurring cases of EPM, which were confirmed positive based on detection of antibodies in the serum and/or CSF and clinical signs, and 20 clinically normal horses were included to determine whether S. neurona altered the immune responses, as measured by immune cell subsets (CD4, CD8, B-cell, monocytes, and neutrophils) and leukocyte proliferation (antigen specific and non-specific mitogens). Our results demonstrated that naturally infected horses had significantly higher percentages of CD4 and neutrophils (PMN) in peripheral blood mononuclear cells (PBMCs) than clinically normal horses. Leukocytes from naturally infected EPM horses had a significantly lower proliferation response, as measured by thymidine incorporation, to a non-antigen specific mitogen phorbol 12-myristate 13-acetate (PMA) / ionomycin (I) than did clinically normal horses (p=0.04). The implications of these findings will be discussed. In experiment 2, 13 horses were randomly divided into two groups. Baseline neurologic examinations were performed and all horses were confirmed negative for S. neurona antibodies in the CSF and serum. Then, one group with 8 clinically normal seronegative horses was inoculated intravenously with approximately 6000 S. neurona infected autologous leukocytes daily for 14 days. All the challenged horses showed neurologic signs consistent with EPM. PBMCs were isolated from the control and infected horses to determine how S. neurona alters the immune responses based on changes in immune cell subsets and immune function. There were no significant differences in the percentage of CD4 cells in peripheral blood lymphocytes or IFN-γ production by CD4 and/or CD8 cells. PMA/I stimulated proliferation responses in PBMCs appeared suppressed compared to that of uninfected controls. Additional studies are necessary to determine the role of CD4 and CD8 cells in disease and protection to S. neurona in horses, as well as to determine the mechanism associated with suppressed in vitro proliferation responses. This project was funded by Patricia Stuart Equine grants and paramutual racing funds from Virginia Tech. / Master of Science