Wilfred Arthur Jefferies

Professor

Relevant Degree Programs

 

Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - May 2019)
ABCF1 is a novel E2 ubiquitin-conjugating enzyme that controls Toll-like receptor-mediated innate immune responses and cytokine storm during sepsis (2018)

No abstract available.

Studies on immune escape mechanism in cancer (2017)

The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.

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The creation of an avian vaccine for West Nile virus (2012)

West Nile Virus (WNV) arrived in North America in 1999 and has since caused significant morbidity and mortality, mainly in birds but also in horses and humans. Many families of birds, especially corvids, are highly susceptible to WNV, with infections often resulting in fatalities. Avian species susceptible to WNV infection also include endangered species, such as the Greater Sage-Grouse (Centrocercus uropbasianuts) and the Eastern Loggerhead Shrike (Lanius ludovicianus migrans). Although WNV is now endemic throughout the continent, to date there is no veterinary vaccine available for birds. This thesis focuses on the use of a recombinant adenovirus to construct vaccines against WNV, that would contain either the envelope or the NS3 ‘genes’ from WNV. To assist in assessing the vaccines, work was undertaken to assess to what extent avian antibody reagents could be used in an avian species for which the antibody was not created. The duck specific CD8 antibody, Du-CD8-1 and the chicken/turkey specific CD4 antibody, CT4, bound to Japanese Quail T cells. The CD4 and CD8 antibody reagents were used to analyse Japanese quail T cell populations, establishing the proportions of CD4+ and CD8+ cells, and discovering a previously unreported population of CD4/CD8 double positive cells. An anti bird IgG antibody was found to bind to chicken, House Sparrow and Japanese Quail IgY; the anti-bird IgG antibody was able to detect IgY from these three species when used as part of a serum ELISA assay. Results from initial vaccine testing in Japanese Quail (Coturnix japonica), indicated that the vaccines activated more T cells and triggered production of higher levels of antibodies in vaccinated birds compared to unvaccinated controls. This was achieved using an intracellular interferon gamma (IFN-γ) assay to assess T cell activation and a serum ELISA to measure levels of WNV specific antibodies. During a challenge assay, using a wild population of House sparrows (Passer domesticus) following infection with WNV, vaccinated birds showed overall reduced levels of viremia compared to unvaccinated controls.

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Characterization of cerebral vascular abnormalities in an Alzheimer’s disease mouse model (2011)

Alzheimer’s disease (AD) patients suffer progressive neurodegenerative loss of memory and other intellectual abilities leading to Dementia, the exact cause of this disease is still unknown. A central pathological hallmark of AD is the presence of an aggregated amyloid-beta peptide (abeta). A strong link between brain vascularity dysfunction and AD exits due to evidence of reduced blood-brain barrier (BBB) integrity preceding other AD neuropatholgies. Furthermore, BBB dysfunction could influence cerebral blood flow, which could in turn influence blood clotting mechanisms during AD. Current dogma holds that AD BBB leakiness is likely due to vascular deterioration and apoptosis. I propose an alternative hypothesis: angiogenesis and hypervascularization underlie increased vascular permeability in AD. Cerebrovascular integrity was characterized in Tg2576 AD model mice by examining the expression of tight junction (TJ) proteins (occludin and ZO-1) with markers of apoptosis and angiogenesis. In aged AD mice, a significant increase in the incidence of disrupted TJs was directly linked to an increased microvascular density, but not apoptosis, which strongly supports hypervascularity as a basis for BBB dysfunction. My results demonstrate that AD related BBB disruption is due to neoangiogenesis, resulting in the redistribution of TJs that maintain the barrier thus providing a new paradigm for connecting vascular remodelling with AD. Unique atypical nonvascular TJ expression was also noted in the aged Tg2576 mice including “halos” of ZO-1 expression surrounding dense-core abeta plaques and occludin expression on a subset of astrocytes sometimes associated with plaques. The observed brain TJ-related pathologies appeared to be linked to the presence of abeta. This argument wasiiistrengthened by observations of Tg2576 mice treated with abeta immunotherapy, which showed reduced brain abeta levels. Tg2576 mice actively immunized with abeta had normal BBB TJ morphology, no apparent occlusions, normal angiogenesis and lacked the unique atypical nonvascular TJ expression. An examination of the general status of the clotting abilities of the Tg2576 mouse was examined. Whole blood from aged Tg2576 mice clotted faster than controls. However, the biochemical components of the clotting cascades were normal, suggesting potential platelet involvement. Taken together, the observed BBB abnormalities will provide new entry points for therapeutic intervention.

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The function of ABCF1 in immunity and mouse development. (2011)

ABCF1 is an ABC (ATP binding cassette) transporter protein that lacks trans-membrane domains. Gene expression of ABCF1 has been shown to increase upon tumour necrosis factor alpha (TNFα) stimulation [1]. This is significant as TNFα is a pro-inflammatory cytokine produced by macrophages and T cells and has a number of functions in the immune response [2]. ABCF1 is thought to function in translational initiation by interacting with the eukaryotic initiation factor 2 (eIF2) [3]. We have determined that ABCF1 is an essential gene in development by the generation and characterization of mice that have a gene trap insertion in the ABCF1 gene, which terminates the expression of the ATP binding cassettes. Homozygous ABCF1 knock-out (ABCF1-/-) mice are embryonic lethal at 3.5 days post coitus (dpc) while heterozygous ABCF1 knock-out (ABCF1+/-) mice appear to be developmentally normal. This thesis utilizes the ABCF1 gene trapped mouse model which contains a β-geo (β-galactosidase /neomycin) reporter gene in the ABCF1 gene to examine the endogenous ABCF1 promoter expression. This allows us to concurrently observe the activity of the ABCF1 promoter in all tissues through sectioning and X-Gal staining. This analysis provides further insight into the physiological function of ABCF1 by identifying the tissues and cell types that have the highest levels of promoter activity. Interestingly, ABCF1 appeared to be expressed in the marginal zone of the spleen and areas surrounding the lymphoid follicles.Macrophages, which were isolated from spleens of ABCF1+/- mice, were found to be hyper-responsive to stimulation by TLR ligands, particularly LPS, while macrophages derived from the bone marrow were found to be hypo-responsive. When challenged with LPS, ABCF1+/- mice produced altered cytokine production compared to their wild-type controls. Upon challenge with Listeria monocytogenes, ABCF1+/- mice succumbed to infection sooner than their ABCF1+/+ littermates. Taken together, these data indicate that ABCF1 is necessary for survival and development and likely has a role in the regulation of cytokines. Thus ABCF1 may play a significant role in regulating inflammation and pathogen induced “cytokine storm”.

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The requirement for competent antigen presenting dendritic cells and poised T cells for immune responses (2011)

Immune responses are initiated by dendritic cells (DCs) that cross present exogenous antigen to naïve T cells. DC cross presentation is essential for generating primary immune responses, yet the mechanistic details remain undefined. Using a CD74⁻/⁻ mouse model, a CD74-MHC I association was shown to mediate trafficking of MHC I from the endoplasmic reticulum to endolysosomal compartments for antigenic loading. These studies describe a novel CD74-mediated cross presentation pathway in DCs that plays a major role in the generation of cytolytic T lymphocyte (CTL) responses against viral and cell-associated antigens. Viruses such as Human Immunodeficiency Virus (HIV) have evolved mechanisms to interfere with immune activation allowing persistence in the host. HIV can infect DCs so the HIV virulence factor, Nef, which interacts with MHC I, has the potential to interfere with MHC I trafficking in the cross presentation pathway. Using a Nef-expressing DC line, Nef was shown to downregulate surface MHC I by inhibiting Golgi-to-surface transport of newly synthesized MHC I and by increasing the recycling of surface MHC I. Coordinately, Nef was shown to inhibit both direct and cross presentation of viral and soluble antigen. Similarly, in a Nef transgenic mouse, Nef was shown to inhibit CTL responses to bacterial and viral infections. This unique immunosubversion mechanism likely contributes to immunodeficiency associated with Acquired Immunodeficiency Syndrome. Peripheral pools of naïve T cells capable of responding to DC stimulus are maintained through homeostatic cues including TCR signalling. Key to this is the second messenger calcium (Ca²⁺); however, the identity of the components regulating intracellular Ca²⁺ concentrations is unclear. Through examination of a knock-out mouse model, the Ca²⁺ channel, CaV1.4, was shown to play a cell-intrinsic role in naïve T cell development and survival. CaV1.4 is critical for regulation of intracellular Ca²⁺ stores and for TCR-induced increases in cytosolic Ca²⁺, which impacts Ras/ERK and NFAT activation. The CaV1.4 deficiency causes a loss of naïve T cells and results in immunodeficiency. These studies reveal a critical function for CaV1.4 in naïve T cell homeostasis. Collectively, this thesis demonstrates the importance of cross presenting DCs and maintenance of T cells for functional immunity.

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The cellular and functional role of melanotransferrin in melanomas (2009)

Melanoma, one of the deadliest forms of skin cancers, is a malignant tumorderived from abnormal proliferation of epidermal melanocytes, and its formation involvesa series of events leading to altered cellular properties and rapid proliferation. Highcellular iron content has been connected to the development of cancers in human. Oneway iron may affect cancer development and progression is by altering cell growth andproliferation. Iron has been proposed to promote progression from G₁ to S phase of thecell cycle through activation of ribonucleotide reductase during DNA synthesis. Iron isnormally absorbed by the enterocyte of the duodenum where it is transported throughoutthe body via serum transferrin. However, the existence of transferrin-transferrin receptorindependent iron transport pathways has been shown. Such pathways are thought to playcritical roles in non-transferrin bound iron overload in diseases such as hemochromatosisand Alzheimer’ s disease, though the molecular details of these pathways remain obscure.Many genes are up-regulated to aid the abnormal proliferation of cancer cellsand subsequent invasion of tissues. In the case of melanoma, the expression ofmelanotransferrin (p97), an iron binding molecule, is elevated. In this thesis, the cellularand functional role of glycosyiphosphatidylinositol (GPI)-anchored p97 in melanoma wasinvestigated. The first aim of this thesis was to perform detailed investigation of theinternalization pathway of GPI-anchored p97 in melanoma cells. Although many GPI anchored proteins have been studied previously, there is still an on-going debate whether caveolae-dependent or clathrin-dependent pathways are involved. Using confocal immunofluorescence microscopy and quantitative immunoelectron microscopy, iron bound GPI-anchored p97 was shown to be internalized via a caveolae vesicles dependent endocytotic pathway. In addition, endosomal disruption studies demonstrated that theintracellular trafficking of the GPI-anchored p97 in melanoma cells is endosomal dependent. The studies performed in this thesis demonstrate that GPI-anchored p97 protein can mediate the iron uptake in melanoma cells. As GPI-anchored p97 is highly expressed in melanoma cells, this thesis also examined the functional role of GPIanchored p97 in melanoma cells and tumors. The expression of GPI-anchored p97 in melanoma cells through over-expression and down-regulation techniques. The results demonstrated that the GPI-anchored p97 promote melanoma cell proliferation, melanin production and secretion in vitro and melanoma tumor growth in vivo. Taken together, this thesis sheds new light on the relationship between GPI-anchored p97, melanomadevelopment and cellular iron uptake.

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Master's Student Supervision (2010 - 2018)
Induction of the antigen presentation machinery using novel small molecules (2017)

The immune system is crucial in the prevention and eradication of cancer. However, cancer genomes mutate more frequently than healthy cells and a commonly acquired phenotype is reduced expression of the antigen presentation machinery (APM) that is required for immunosurveillance. This phenotype can allow cancer cells to become invisible to the immune system and metastasize with limited inhibition. Since this phenomenon is seen across a wide variety of cancers discovering methods to reverse this immune evasion could lead to the development of widely applicable therapeutics.A compound, S-(+)-curcuphenol was previously identified as a novel candidate for restoring expression of the APM, however, its synthesis is greatly hindered due to chirality. Therefore, I investigated the ability of curcuphenol analogues to induce expression of the major histocompatibility complex I (MHC-I) in a murine metastatic lung carcinoma cell line in vitro. Two derivatives of curcuphenol, P02-113 and P03-97-1, showed improved outcomes in vitro and I further evaluated them in vivo, as anti-cancer therapeutics. Both compounds reduced tumour burden and increased immune cell infiltration into tumours.To explore a potential mechanism of P02-113 and P03-97-1, I evaluated them for histone deacetylase (HDAC) inhibition based on structural similarity to established HDAC inhibitors. Upon examination I observed a completely novel effect of enhanced class I/II HDAC activity. Furthermore to identify if this effect was direct and to uncover which HDAC enzymes were being affected, I evaluated individual HDAC enzymes. I discovered that HDAC8 was inhibited by both P02-113 and P03-97-1, however, the activities of HDAC 5 and 10 were enhanced upon treatment.While the field of cancer immunotherapy has grown, few therapeutics have been identified to target loss of immunogenicity through the up-regulation of the APM. In this thesis two analogues of curcuphenol P02-113 and P03-97-1 have been identified that up- regulate the APM in vitro and reduce tumour burden in vivo. With these effects P02-113 and P03-97-1 hold great potential as future therapeutics for cancers exhibiting an immunodeficient phenotype through loss of the APM. As well these compounds presentiithe first class II HDAC enhancers, as they increase the enzymatic activity of HDAC 5 and 10.

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Altered clot formation and anticoagulation in a familial Alzheimer's disease mouse model (2013)

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the leading form of dementia. Its complex etiology is traditionally attributed to an increase in the production and aggregation of amyloid-beta (Aβ). However, vascular risk factors and related disorders are also associated with the development of AD. The mechanism by which these deficiencies lead to neurodegeneration remains unclear. An altered hemostatic state has increasingly been implicated in AD pathogenesis, with the majority of research focusing on the interaction between Aβ and fibrin. It was therefore of interest to assess previously uncharacterized components of coagulation and anticoagulation in a familial AD (FAD) mouse model. Clot formation was initially analyzed using platelet rich plasma, with aged AD mice exhibiting 40% shorter clotting times compared to age-matched controls. Thrombin generation revealed differences attributable to an altered clot integrity. AD mice may form clots composed of a dense network of thin fibrin strands, resistant to fibrinolysis. Correspondingly, antithrombin (AT) activity was also reduced. These changes were subject to age, occurring specifically in aged mice only. These data suggest a change in clot formation and integrity concomitant with the development of AD. The interaction between Aβ and AT was examined in vitro, with Aβ42 and Aβ40 decreasing AT activity in a concentration dependent manner. A clinical study evaluating prothrombotic markers revealed a trend towards lower AT activity in AD patients, though not statistically significant. The changes in clot formation and anticoagulation potentiating a prothrombotic state may be specific to the FAD mouse model, but may still contribute to the elucidation of AD pathogenesis.

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The role of Cav1.4 calcium channel in T cell activation, proliferation, effector functions and death (2010)

T lymphocytes are an important part of the immune system that identify and destroy foreign antigens in the body as well as activate and deactivate other immune cells. In T lymphocytes, calcium is a secondary messenger that regulates activation and proliferation, effector function, survival and death. Although calcium release from the intracellular stores within T lymphocytes is well characterized, the calcium entry pathway from extracellular sources into T lymphocytes is unclear, despite contributing to the majority of elevated intracellular calcium ions during T lymphocyte activation. Preliminary studies have shown that L-type calcium channels play significant roles in the calcium influx pathways, mediating T lymphocyte activation and proliferation in vitro. Cav1.4 L-type calcium channel has been found to be expressed in both mouse and human T lymphocytes. To date, three Cav1.4 calcium channel splice variants have been identified with differential expression throughout the T lymphocyte proliferation process. I hypothesized that pore forming subunit of a L-type calcium channel, Cav1.4, regulates T lymphocyte activation and proliferation in vivo. To test this hypothesis, I used loss of function L-type calcium channel knock-out (KO) mice lacking the entire gene coding for this calcium channel and its splice variants to study its effects on T cell activation, proliferation, death, calcium uptake, and effector responses. From these studies, I predict that the lack of L-type calcium channels will cause T lymphocyte activation, proliferation and development to be impaired. These studies shed light on the mechanism of T lymphocyte activation and also enabled us to better understand how antagonistic drugs such as nifedipine may cause immunosuppressive effects.

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