Copies of author's previously published articles inserted. / Includes bibliographical references. / vii, 39 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Shows that the cytokine tumour necrosis factor [alpha] (TNF-[alpha]) enhances the adhesion of neutrophils to the endothelium by an action both on the neutrophil and on the endothelial cell. / Thesis (Ph.D.)--University of Adelaide, Dept. of Microbiology and Immunology, 1995?

Niemann-Pick Type C (NPC) disease is an autosomal recessive disorder that results in accumulation of unesterified cholesterol in late endosomes/lysosomes (LE/Ls), leading to progressive neurodegeneration and premature death. Microglia are resident immune cells of the central nervous system, which upon activation can secrete potentially neurotoxic molecules such as tumor necrosis factor-alpha (TNFα). Inappropriate activation of microglia has been implicated in NPC disease. Primary microglia cultures from the cerebral cortex of Npc1-/- mice have an altered cholesterol distribution characteristic of NPC-deficient cells. Immunocytochemical analysis revealed increased TNFα staining in Npc1-/- microglia. However, Npc1-/- and Npc1+/+ microglia showed similar mRNA levels of pro-inflammatory cytokines and similar levels of TNFα secretion. To determine whether Npc1-/- microglia contribute to neuron death in NPC disease, microglia were co-cultured with cerebellar granule cells. Surprisingly, the extent of neuronal death was the same in neurons cultured with Npc1+/+ or Npc1-/- microglia. Thus, Npc1-/- microglia have an altered phenotype compared to Npc1+/+ microglia, but this does not lead to neuron death in an in vitro co-culture system. Treatment options for NPC disease remain limited. A consequence of cholesterol sequestration in the LE/Ls, is that cholesterol movement to the endoplasmic reticulum, where cholesterol metabolism is regulated, is impaired. Cyclodextrin (CD), a compound that binds cholesterol, has recently been found to delay the onset of neurological symptoms and prolong life of Npc1-/- mice. Since the brain consists of both neurons and glia, it remains unclear if CD acts directly on neurons and/or other cells in the brain. Neurons cultured from the cerebellum and astrocytes cultured from the cortex of Npc1-/- mice were treated with a low dose (0.1mM) of CD. This treatment decreased cholesterol sequestration and decreased the rate of cholesterol synthesis in Npc1-/- neurons and astrocytes. CD also decreased mRNAs encoding proteins involved in cholesterol synthesis in Npc1-/- neurons and increased genes involved in cholesterol efflux in Npc1-/- astrocytes. Moreover, CD increased cholesterol esterification in Npc1-/- astrocytes. These results suggest that cholesterol trapped in LE/Ls in Npc1-/- neurons and astrocytes was released by CD treatment and reached the ER, thereby regulating cholesterol homeostasis. / Experimental Medicine

Thesis (Ph. D.)--University of Chicago, Committee on Immunology, June 2003. / Includes bibliographical references. Also available on the Internet.

<p><i>S. sclerotiorum</i> has been studied for over 100 years. Despite this, a definite resistance mechanism to this plant pathogen remains to be identified. Researchers continue to examine the <i>S. sclerotiorum</i> life cycle to identify stages where effective disease management strategies can be applied. The development of molecular tools has allowed for a better understanding of the pathogen and created new opportunities for research on plant-pathogen interactions.</p> <p>Most of the past research on pathogenicity factors produced by this pathogen, such as hydrolytic enzymes, studied them in isolation. This thesis examines how <i>S. sclerotiorum</i> pathogenicity factors, including cutinases, polygalacturonases and necrosis-inducing peptides, work in concert during the infection. The first study explored processes for cuticle penetration leading to the identification of the gene encoding S. sclerotiorum cutinase A and the characterization of the factors that govern its expression during the infection. The second study investigated how the pathogen penetrates the cell wall and proliferates within the host. In this regard, the mechanism with which expression of <i>S. sclerotiorum</i> polygalacturonase genes is regulated was elucidated. The interplay with host polygalacturonase inhibitor proteins was also demonstrated and related to the mechanisms of host resistance. The third study examined factors involved in tissue necrosis and two necrosis-inducing proteins were characterized. This study also unraveled part of the signaling mechanisms that allow for the pathogen to regulate pathogenicity gene expression during the infection. The signaling mechanisms were found to involve calcium, cAMP and at least one <i>S. sclerotiorum</i> mitogen activated protein kinase (SMK3) working in concert to coordinate the infection process. SMK3 was found to play a major role in a variety of vital functions, such as mycelial branching, infection cushion formation and sclerotia production. Genetic transformation of <i>S. sclerotiorum</i> was required to enable certain aspects of this study. My approach to this led to the development of a highly efficient method to isolate homokaryotic lines of filamentous fungi. In conclusion, this thesis has advanced the understanding of <i>S. sclerotiorum</i>-host interactions and identified a number of factors involved in pathogenesis.</p>

This thesis evaluated supplementation with two components of flaxseed during exercise training on inflammation in older adults.<P>Experiment 1: This experiment assessed secoisolariciresinol diglucoside (SDG) supplementation during aerobic exercise training on inflammation in older adults. Methods: One hundred subjects aged 50y or older were randomized to receive either SDG or placebo before completing a 6-month walking program. Fasting concentrations of interleukin-6 and tumor necrosis factor-á, glucose, triacylglycerol (TAG), high density lipoprotein (HDL), low density lipoprotein, and total cholesterol as well as leukocyte cell count were measured every two months while body composition, resting blood pressure, and a composite Z-score of six metabolic syndrome risk factors were assessed at baseline and 6 months. Results: Men on placebo increased metabolic syndrome composite Z-score (p<0.05). TAG increased (p=0.017) in men on placebo relative to men on SDG and men on SDG decreased (p=0.045) DBP relative to men on placebo. Conclusions: SDG had no effect on inflammation while it is effective in attenuating risk factors associated with metabolic syndrome in older males but not females.<p>Experiment 2: This experiment evaluated alpha-linolenic acid (ALA) supplementation during strength exercise training on inflammation in older adults. Methods: Fifty-one healthy older adults (65.4±0.8y) were randomized to receive ALA or a placebo before completing a 12 wk strength training program. Subjects were evaluated at baseline and 12 weeks for TNF-á and IL-6, muscle strength, body composition, and muscle thickness. Results: Males supplementing with ALA decreased IL-6 concentration (p=0.003). The female placebo and male ALA group had a significant increase in knee flexor thickness (p<0.05). Chest and leg press strength, lean tissue mass, and muscle thickness significantly increased, while percent fat and total body mass decreased with training (p<0.05), with no difference between ALA and placebo. Conclusions: ALA lowers IL-6 in older men, but has minimal effect on muscle mass and strength during resistance training.<p>General Conclusion: A composite score of metabolic syndrome is attenuated in males supplementing with SDG. ALA reduces IL-6 in older men. Older men, but not older women, derive specific health benefits from increased consumption of components of flaxseed consumed during an exercise program.

<p><i>S. sclerotiorum</i> has been studied for over 100 years. Despite this, a definite resistance mechanism to this plant pathogen remains to be identified. Researchers continue to examine the <i>S. sclerotiorum</i> life cycle to identify stages where effective disease management strategies can be applied. The development of molecular tools has allowed for a better understanding of the pathogen and created new opportunities for research on plant-pathogen interactions.</p> <p>Most of the past research on pathogenicity factors produced by this pathogen, such as hydrolytic enzymes, studied them in isolation. This thesis examines how <i>S. sclerotiorum</i> pathogenicity factors, including cutinases, polygalacturonases and necrosis-inducing peptides, work in concert during the infection. The first study explored processes for cuticle penetration leading to the identification of the gene encoding S. sclerotiorum cutinase A and the characterization of the factors that govern its expression during the infection. The second study investigated how the pathogen penetrates the cell wall and proliferates within the host. In this regard, the mechanism with which expression of <i>S. sclerotiorum</i> polygalacturonase genes is regulated was elucidated. The interplay with host polygalacturonase inhibitor proteins was also demonstrated and related to the mechanisms of host resistance. The third study examined factors involved in tissue necrosis and two necrosis-inducing proteins were characterized. This study also unraveled part of the signaling mechanisms that allow for the pathogen to regulate pathogenicity gene expression during the infection. The signaling mechanisms were found to involve calcium, cAMP and at least one <i>S. sclerotiorum</i> mitogen activated protein kinase (SMK3) working in concert to coordinate the infection process. SMK3 was found to play a major role in a variety of vital functions, such as mycelial branching, infection cushion formation and sclerotia production. Genetic transformation of <i>S. sclerotiorum</i> was required to enable certain aspects of this study. My approach to this led to the development of a highly efficient method to isolate homokaryotic lines of filamentous fungi. In conclusion, this thesis has advanced the understanding of <i>S. sclerotiorum</i>-host interactions and identified a number of factors involved in pathogenesis.</p>

This thesis evaluated supplementation with two components of flaxseed during exercise training on inflammation in older adults.<P>Experiment 1: This experiment assessed secoisolariciresinol diglucoside (SDG) supplementation during aerobic exercise training on inflammation in older adults. Methods: One hundred subjects aged 50y or older were randomized to receive either SDG or placebo before completing a 6-month walking program. Fasting concentrations of interleukin-6 and tumor necrosis factor-á, glucose, triacylglycerol (TAG), high density lipoprotein (HDL), low density lipoprotein, and total cholesterol as well as leukocyte cell count were measured every two months while body composition, resting blood pressure, and a composite Z-score of six metabolic syndrome risk factors were assessed at baseline and 6 months. Results: Men on placebo increased metabolic syndrome composite Z-score (p<0.05). TAG increased (p=0.017) in men on placebo relative to men on SDG and men on SDG decreased (p=0.045) DBP relative to men on placebo. Conclusions: SDG had no effect on inflammation while it is effective in attenuating risk factors associated with metabolic syndrome in older males but not females.<p>Experiment 2: This experiment evaluated alpha-linolenic acid (ALA) supplementation during strength exercise training on inflammation in older adults. Methods: Fifty-one healthy older adults (65.4±0.8y) were randomized to receive ALA or a placebo before completing a 12 wk strength training program. Subjects were evaluated at baseline and 12 weeks for TNF-á and IL-6, muscle strength, body composition, and muscle thickness. Results: Males supplementing with ALA decreased IL-6 concentration (p=0.003). The female placebo and male ALA group had a significant increase in knee flexor thickness (p<0.05). Chest and leg press strength, lean tissue mass, and muscle thickness significantly increased, while percent fat and total body mass decreased with training (p<0.05), with no difference between ALA and placebo. Conclusions: ALA lowers IL-6 in older men, but has minimal effect on muscle mass and strength during resistance training.<p>General Conclusion: A composite score of metabolic syndrome is attenuated in males supplementing with SDG. ALA reduces IL-6 in older men. Older men, but not older women, derive specific health benefits from increased consumption of components of flaxseed consumed during an exercise program.

<p>Mast cells, best known for their pathologic role in allergy, have recently been shown to have key roles in the initiation of adaptive immune responses. These cells are located throughout the body just beneath barriers separating host from environment, possess multiple pathogen recognition systems, and store large quantities of fully active inflammatory mediators. These key features make them uniquely situated to act as sentinels of immunity, releasing the very earliest alarm signals when a pathogen is present. As a testament to the importance of these cells, mast cell-deficient mice have suboptimal immune responses, and mast cell activators can act as potent adjuvants for experimental immunizations. Specifically, mast cells have been shown to enhance the number of naive lymphocytes in infection site-draining lymph nodes, and to encourage the migration of dendritic cells to responding lymph nodes.</p><p>Although infections usually occur at peripheral sites, adaptive immune responses are initiated in distant lymph nodes. Despite the distance, signals from the site of infection result in dramatic, rapid reorganization of the node, including massive recruitment of naive lymphocytes from the circulation and extensive vascular restructuring to accommodate the increase in size. How such signals reach the lymph node is not well understood.</p><p>When mast cells degranulate, in addition to releasing soluble mediators such as histamine, they expel large, stable, insoluble particles composed primarily of heparin and cationic proteins. The work presented herein demonstrates that these particles act as extracellular chaperones for inflammatory mediators, protecting them from dilution into the interstitial space, degradation, and interaction with non-target host cells and molecules. The data show clearly that mast cells release such particles, that they are highly stable, that they contain tumor necrosis factor (a critically important immunomodulator), and that they can traffic from peripheral sites to draining lymph nodes via lymphatic vessels. Furthermore, extensive biochemical characterization of purified mast cell-derived particles was performed. Finally, evidence is presented that such particles can elicit lymph node enlargement, an infection-associated phenomenon that favors the development of adaptive immunity, by delivering peripheral TNF to draining lymph nodes. </p><p>This signaling concept, that particles may chaperone signals between distant sites, also has important implications for adjuvant design. The evidence presented here shows that encapsulation of TNF into synthetic particles similar to mast cell-derived particles greatly enhances its potency for eliciting lymph node enlargement, an indication that adaptive immunity may be improved. This delivery system should ensure that more adjuvant arrives in the draining lymph node intact, where it would lead to changes favorable to the development of the immune response. Such a system would also facilitate the delivery of multi-component adjuvants that would act synergistically at the level of the lymph node when gradually released from microparticle carriers. An additional advantage of microparticle encapsulation is that vaccine formulations of this type may require much lower doses of expensive antigen and adjuvants.</p><p>The delivery of inflammatory mediators to lymph nodes during immune responses may be an important general feature of host defense. Although the action of mediators of peripheral origin on draining lymph nodes has been described before, this is the first demonstration of a specific adaptation to deliver such mediators. Not only is the characterization of mast cell-derived particles important to basic immunology, but mimicking this adaptation may also lead to improved therapeutics.</p> / Dissertation

Grouper nervous necrosis viruses belong to the Betanodavirus genus in the Nodaviridae family that is a group of small, non-enveloped icosahedron viruses. More than 30 species of fish are infected by the betanodaviruses, which cause massive mortality in hatchery-reared larvae and juveniles. The infection causes great economic losses to aquaculture and sea-ranching. To study the effects of N-terminus and disulfide bonds of capsid protein on particle formation and thermal stability of grouper nervous necrosis virus, virus-like particles (VLPs) of dragon grouper nervous necrosis virus (DGNNV) were used. Deletion of 35 residues at the N-terminus completely ruined the VLP assembly. When deletions were restricted to 4, 16, or 25 N-terminal residues, the assembly of VLPs remained. Site-directed mutagenesis was used to investigate the effects of N-terminus of capsid protein on particle formation and thermal stability of grouper nervous necrosis virus. Althought all arginine mutants could produce VLPs, the relative amounts and thermal stabilities of arginine-mutated VLPs were decrease. The VLPs from £GN25-R29A and £GN25 mutants have similar structural properties on particle formation and thermal stability. Therefore, the effects of Arg29 mutations are negligible. The relative amounts and thermal stabilities of VLPs from £GN25-R30A and £GN25-R31A mutants are lower than £GN25-R29A VLP. When 25 amino acids at N-terminus of DGNNV capsid protein were removed, Arg30 and Arg31 are important for particle formation and particel stability. Although particle could form as 12 positively charged amino acids were lost (¡µN25-R293031A), the efficiency of particles assembly were decrease to 1.2 ¡Ó 0.9% as compare to wild-type VLPs (WT-VLPs). Site-directed mutagenesis and chemical reducing reagents were used to investigate the roles of disulfide bonds in particle formation and thermal stability of grouper nervous necrosis virus. The homogeneous particles from C187A, C331A and C187A/C331A mutants are indistinguishable from the native virus and WT-VLPs in their sizes and shapes. C115A and C201A mutants could not produce VLPs. The dissociated capsomers from arginine- or cysteine-mutant VLPs all can be reassembled to icosahedrons with efficiencies as high as 100%. When VLP particles are pre-fabricated, the reducing agent cannot disrupt the VLP icosahedron structure. The thiol reduction only caused effects on the disulfide linkages inside the icosahedrons. £]-mercaptoethanol-treated WT-VLPs could not tolerate the thermal effects at a temperature higher than 70¢XC. Once the disulfide linkages in dissociated capsomers were entirely disrupted by £]-mercaptoethanol treatment, the resulting capsomers could not reassemble back to icosahedron particles.These results indicated that Cys115 and Cys201 were essential for capsid formation of DGNNV icosahedron structure in de novo assembly and reassembly pathways, as well as for the thermal stability of pre-fabricated particles. In the observation of Cryo-EM, the shapes and sizes of the N-terminus truncated particle (£GN25-VLP) are indistinct from the full-length particle (WT-VLP). The maximum diameter of DGNNV is approximately 380 Å. Like that of the insect nodaviruses, the surface morphologies of £GN25-VLP and WT-VLP are consistent with a T = 3 quasi-equivalent lattice. The protrusions (~154 to 192 Å), the inner shell of the capsid (~112 to 154 Å), and the RNA (¡Õ112 Å) were observed in the DGNNV structure. The protrusion domain is consisting of three capsid subunits, and the interactions between these subunits are different. Deletion of 25 residues at the N-terminus did not affect VLPs formation and the structure of £GN25-VLP is similar to WT-VLPs. Resolutions was calculated by Fourier shell correlation, and the resolution of WT-VLPs and £GN25-VLPs is 6.5Å and 11.8Å, respectively.

In order to investigate the effects of C-terminus modification of Dragon Grouper Nervous Necrosis Virus capsid protein on the virus particle formation, we used E. coli expression system to express DGNNV capsid protain with different truncations at C-teminus fused with six or three histidines (His-Tag). These poly-His tagged clones, including ¡µC334-C6H, ¡µC335-C6H, ¡µC336-C6H, ¡µC337-C6H, C3H and C6H (His6 tagged at the C-teminus of wild-type capsid protein)¡Awere expressed and VLPs formation ability were examined. Wild-type and N-terminal recombination (N6H, His6 tagged at the N-teminus of wild-type capsid protein) were also used for comparison. These His-tagged VLPs can be further purified by Ni-NTA agarose, and their thermal stability of mutant VLPs were analyzed by Circular Dichroism. The Western blotting and ELISA assay were utilized to analyzed N-teminus or C-terminus was located at the surface of virus icosahedron. Once the four amino acids at the C-terminus of capsid protein were truncated (¡µC334-C6H), the mutated cpasid protein cannot assemble into VLPs. The same phenomenon was also observed in C6H. The related productions of wild-type, ¡µC335-C6H, ¡µC336-C6H, ¡µC337-C6H, C3H VLPs were about 100%, 56%, 116%, 141%, and 193%, respectively. Using Circular Dichroism to observe the thermal stability of mutant VLPs, the results revealed that the Tm of mutant VLPs were about 3oC lower than wild-type VLPs (61oC). The results of Western blotting and ELISA assay suggest that the C-termius of DGNNV capisid protein was exposed to the surface of virus structure.