The family Adenoviridae consists of five genera, including the genus Aviadenovirus, which infects avian species. The genus Aviadenovirus currently comprises five fowl (Fowl adenovirus A-E), one falcon (Falcon adenovirus A), and one goose (Goose adenovirus) adenovirus species. Fowl adenoviruses (FAdVs) have a worldwide distribution. Some are associated with diseases such as inclusion body hepatitis (IBH), while FAdV species C serotype 4 (FAdV-4) has been associated with hydropericardium-hepatitis syndrome (HHS). In this study, the complete nucleotide sequence of fowl adenovirus serotype 8 (FAdV-8) was determined. The full genome was 44,055 nucleotides (nt) in length, with an organization similar to that of the FAdV-1 and FAdV-9 genomes. No regions homologous to early regions E1, E3, and E4 of mastadenoviruses were recognized Pathogenicity of FAdV-8 and FAdV-4 were studied in specific-pathogen-free chickens following oral and intramuscular inoculations. Pathogenicity was determined on the basis of clinical signs and gross and histological lesions. Additionally, virus shedding and viral genome copy numbers in liver, cecal tonsil, and bursa of Fabricius were determined. The role of interleukins (IL) in the pathogenicity of and immune response to FAdVs is unknown. Therefore, in a chicken experiment, interferon-γ, IL-10, IL-18, and IL-8 gene expression was evaluated following FAdV-8 and FAdV-4 infection. Cytokine gene expression was examined in the liver, spleen, and cecal tonsils. This study explored the ability of fowl adenoviruses to subvert the host cell’s secretion of cytokines in response to infection as an important viral mechanism for immune evasion during infection. Variations in virulence of FAdVs are likely to be determined by the fiber alone as shown by Pallister et al. (1996). Therefore, we compared and analyzed the nt and amino acid (aa) sequences of the fiber gene of pathogenic and non-pathogenic FAdVs representing species groups D (FAdV-11) and E (FAdV-8). According to our data, virulence might not be associated only with sequence of the fiber gene. This work is a continuation of our efforts towards better understanding of the molecular biology of FAdVs and the pathogenesis of the disease, with an emphasis on the role of interleukins, an unknown area.

Mast cells are granulocytes that are a key component of the innate and adaptive immune system, and contribute to allergic disorders. Mast cell activation following clustering of the high affinity IgE receptor (FcepsilonRI) by multivalent antigens requires reversible tyrosine phosphorylation of myriad signaling proteins. Activated mast cells rapidly release granule contents (eg. histamine and serine proteases) that cause vascular permeability, and in a more delayed manner they also synthesize and secrete eicosanoids and numerous cytokines (eg. IL-6 and TNFalpha) that recruit activated leukocytes. FcepsilonRI signaling is initiated by Lyn, a Src Family Kinase (SFK), that phosphorylates immunoreceptor tyrosine-based activation motifs (ITAMs) found on the FcepsilonRI beta and gamma chains. This allows recruitment of Fyn SFK and Syk kinase that bind ITAMs and phosphorylate numerous downstream targets. Src Homology 2 domain-containing Phosphatase 2 (SHP2, encoded by ptpn11/shp2) is known to be recruited to several phosphorylated proteins following FcepsilonRI aggregation in mast cells, however attempts to define the role of SHP2 have been hampered by its essential role during embryonic development and hematopoiesis in mice. Recently, conditional SHP2 knock-out mice (shp2fl/fl) have been created allowing for shp2 inactivation in a tissue-specific manner by Cre recombinase. Here we describe the use of transgenic mice expressing a modified estrogen receptor-Cre Recombinase (TgCreER*) on a shp2fl/fl genetic background, that allows for maturation of bone marrow-derived mast cells (BMMCs) prior to shp2-inactivation using 4-hydroxytamoxifen (4OH-TM). SHP2-depleted BMMCs display reduced phosphorylation of the FcepsilonRI beta chain, but exhibit extended phosphorylation of Syk kinase. Additionally, SHP2-deficient cells display a defect in the activation of both Erk mitogen-activated protein kinase and Akt, which correlates with an observed defect in the production of TNFalpha and Leukotriene C4. Finally, we show that SHP2-deficient BMMCs display elevated FcepsilonRI-evoked phosphorylation of Csk-Binding Protein (Cbp or PAG) on residue Y317, which recruits C-terminal Src kinase (Csk) that phosphorylates SFKs on an inhibitory tyrosine. This hyperphosphorylation of Cbp correlates with elevated phosphorylation of the C-terminal inhibitory tyrosine on Fyn kinase. This study provides new insights into the role of SHP2 as a positive effector of FcepsilonRI signaling and cytokine production in mast cells. / Thesis (Master, Biochemistry) -- Queen's University, 2008-08-20 13:51:18.751

Spontaneous term labour is associated with increased inflammatory events in the myometrium including cytokine production and leukocyte infiltration. We hypothesized that mechanical stretch of the uterine wall by the growing fetus facilitates peripheral leukocyte transendothelial migration into the term pregnant myometrium through the release of various cytokines. The current study demonstrated that static mechanical stretch directly induces secretion of multiple cytokines and chemokines by human myometrial smooth muscle cells. Stretch-induced cytokines (1) increased vascular permeability; (2) enhanced leukocyte adhesion to the endothelium of the surrounding uterine microvasculature by (3) inducing the expression of endothelial cell adhesion molecules; and (4) directed the transendothelial migration of peripheral neutrophils. Our data provide a direct proof of mechanical regulation in leukocyte recruitment from the uterine blood vessels, which represents a putative mechanism for the leukocyte infiltrate seen in the myometrium during labour and postpartum involution.

Spontaneous term labour is associated with increased inflammatory events in the myometrium including cytokine production and leukocyte infiltration. We hypothesized that mechanical stretch of the uterine wall by the growing fetus facilitates peripheral leukocyte transendothelial migration into the term pregnant myometrium through the release of various cytokines. The current study demonstrated that static mechanical stretch directly induces secretion of multiple cytokines and chemokines by human myometrial smooth muscle cells. Stretch-induced cytokines (1) increased vascular permeability; (2) enhanced leukocyte adhesion to the endothelium of the surrounding uterine microvasculature by (3) inducing the expression of endothelial cell adhesion molecules; and (4) directed the transendothelial migration of peripheral neutrophils. Our data provide a direct proof of mechanical regulation in leukocyte recruitment from the uterine blood vessels, which represents a putative mechanism for the leukocyte infiltrate seen in the myometrium during labour and postpartum involution.

The abomasal helminth Teladorsagia circumcincta is one of the most economically important parasites to affect the farming of sheep and goats. T.circumcincta infection is particularly detrimental to lambs, in which it can cause pronounced morbidity and severe production losses. Due to the spreading resistance of this parasite to all currently available classes of anthelmintic drugs, it is having an increasingly severe impact on the sheep industry with significant implications for sheep welfare. Infection of sheep with T.circumcincta triggers local changes in the abomasum characteristic of a T helper type-2 (Th2) driven immune response, including local eosinophilia, mastocytosis and increased mucus production, which leads to expulsion of the parasite. However, this protective immunity develops slowly during repeated exposure, wanes rapidly, and does not appear to be evident in young lambs. Vaccination to provoke early onset of protective immunity has therefore been suggested as an alternative means of control in the face of spreading anthelmintic resistance. Greater understanding of the development of immunity to T.circumcincta, and why this is delayed in lambs, would be useful in vaccine development. This thesis focuses on cytokine transcription profiling of the ovine abomasal mucosa and local lymphatic tissues. Changes in cytokine transcription over the course of a challenge infection with T.circumcincta were defined in helminth naïve sheep, and in previously infected sheep which have developed a degree of immunity during an eight week trickle infection, to clarify the mechanisms by which this immunity is orchestrated. This work demonstrated a clear Th2 cytokine response in the abomasal mucosa over the course of infection, which developed earlier and was more pronounced in the previously infected sheep; possibly owing to a population of polarised Th2-type cells built up during the previous infection. Suppression of Th1 cytokine transcription was also a prominent finding in the draining lymph node, which likewise occurred earlier in the previously infected sheep. Repetition of this experiment using younger lambs provided a possible explanation for the reduced resistance to T.circumcincta in this age group. While Th2 and proinflammatory cytokine responses in the abomasal mucosa demonstrated similar trends to those found in the older sheep, little suppression of Th1 cytokine transcription was observed in the draining lymph node. It is therefore suggested that the increased susceptibility of young lambs to T.circumcincta is not due to an inability to generate adequate Th2 responses, but an inability to suppress transcription of antagonistic Th1 cytokines.

Negative regulation of cytokine signalling is essential for maintaining hematopoietic homeostasis. We investigated the role of SH2B1 and CBL in the negative regulation of EPO and GM-CSF signaling, respectively. Erythropoiesis is driven by the cytokine erythropoietin (EPO), which mediates its signal by binding to its cognate receptor, the erythropoietin receptor (EPO-R). Murine knock-in studies have demonstrated EPO-R Tyr343 to play an important role in EPO mediated signalling. We have utilized a Cloning of Ligand Target (COLT) screen to identify the adaptor protein SH2B1 as an interactor of EPO-R pTyr343. We have demonstrated that SH2B1 binds to EPO-R via two mechanisms. The amino-terminus of SH2B1 and the membrane proximal region of EPO-R mediate SH2B1 constitutive binding to EPO-R. SH2B1 binds to EPO-R pTyr343 and pTyr 401 in an SH2 domain-dependent manner. SH2B1 displayed dose- and time- dependent Serine/Threonine phosphorylation in response to EPO stimulation. Knockdown of SH2B1 resulted in enhanced activation of Jak2 and EPO-R. These studies demonstrate SH2B1 as a novel negative regulator of EPO signalling. Mutations in the linker region and the RING finger of CBL have been identified in a number of myeloid malignancies, including juvenile myelomonocytic leukemia. We investigated how linker region mutant, CBL-Y371H, and RING finger mutant, CBL-C384R lead to GM-CSF hypersensitivity. Expression of these CBL mutants in the human hematopoietic cell line, TF-1, showed enhanced stimulation induced phosphorylation of GM-CSFR βc. We also demonstrated that the loss of E3 ligase activity of these CBL mutants results in increased expression of JAK2 and LYN kinases. Assessment of the effects of CBL mutants on downstream signalling revealed enhanced phosphorylation of SHP2, CBL and S6. Dasatinib induced inhibition of SRC family kinases abolished the elevated phosphorylation of CBL mutants, and equalized the phosphorylation of GM-CSFR βc in the wild type and CBL mutant cells.

B-cell acute lymphoblastic leukemia (B-ALL) represents a collection of diseases that are categorized into subtypes based on the presence of recurrent cytogenetic abnormalities. These abnormalities often result in the expression of oncogenic drivers that denote a standard- or high-risk for relapse. Currently, survival rates boarder 40% for adult patients and relapses are often observed in patients lacking high-risk markers. Thus, there is an unmet need for biomarkers that can identify all high-risk leukemia, and development of novel therapies based on a better understanding of the molecular drivers of B-ALL. To address this need, I designed a multi-parameter phospho-flow cytometry platform and characterized basal and cytokine-potentiated signaling in adult B-ALL samples. I identified patterns of cytokine-responsiveness across B-ALL patients that correlated with the presence of high-risk oncogenic drivers. Furthermore, I demonstrated that small-molecule inhibitors could abrogate cytokine-induced signaling in high-risk patients suggesting these inhibitors may compliment current chemotherapeutic protocols.

Negative regulation of cytokine signalling is essential for maintaining hematopoietic homeostasis. We investigated the role of SH2B1 and CBL in the negative regulation of EPO and GM-CSF signaling, respectively. Erythropoiesis is driven by the cytokine erythropoietin (EPO), which mediates its signal by binding to its cognate receptor, the erythropoietin receptor (EPO-R). Murine knock-in studies have demonstrated EPO-R Tyr343 to play an important role in EPO mediated signalling. We have utilized a Cloning of Ligand Target (COLT) screen to identify the adaptor protein SH2B1 as an interactor of EPO-R pTyr343. We have demonstrated that SH2B1 binds to EPO-R via two mechanisms. The amino-terminus of SH2B1 and the membrane proximal region of EPO-R mediate SH2B1 constitutive binding to EPO-R. SH2B1 binds to EPO-R pTyr343 and pTyr 401 in an SH2 domain-dependent manner. SH2B1 displayed dose- and time- dependent Serine/Threonine phosphorylation in response to EPO stimulation. Knockdown of SH2B1 resulted in enhanced activation of Jak2 and EPO-R. These studies demonstrate SH2B1 as a novel negative regulator of EPO signalling. Mutations in the linker region and the RING finger of CBL have been identified in a number of myeloid malignancies, including juvenile myelomonocytic leukemia. We investigated how linker region mutant, CBL-Y371H, and RING finger mutant, CBL-C384R lead to GM-CSF hypersensitivity. Expression of these CBL mutants in the human hematopoietic cell line, TF-1, showed enhanced stimulation induced phosphorylation of GM-CSFR βc. We also demonstrated that the loss of E3 ligase activity of these CBL mutants results in increased expression of JAK2 and LYN kinases. Assessment of the effects of CBL mutants on downstream signalling revealed enhanced phosphorylation of SHP2, CBL and S6. Dasatinib induced inhibition of SRC family kinases abolished the elevated phosphorylation of CBL mutants, and equalized the phosphorylation of GM-CSFR βc in the wild type and CBL mutant cells.

B-cell acute lymphoblastic leukemia (B-ALL) represents a collection of diseases that are categorized into subtypes based on the presence of recurrent cytogenetic abnormalities. These abnormalities often result in the expression of oncogenic drivers that denote a standard- or high-risk for relapse. Currently, survival rates boarder 40% for adult patients and relapses are often observed in patients lacking high-risk markers. Thus, there is an unmet need for biomarkers that can identify all high-risk leukemia, and development of novel therapies based on a better understanding of the molecular drivers of B-ALL. To address this need, I designed a multi-parameter phospho-flow cytometry platform and characterized basal and cytokine-potentiated signaling in adult B-ALL samples. I identified patterns of cytokine-responsiveness across B-ALL patients that correlated with the presence of high-risk oncogenic drivers. Furthermore, I demonstrated that small-molecule inhibitors could abrogate cytokine-induced signaling in high-risk patients suggesting these inhibitors may compliment current chemotherapeutic protocols.

Title page, abstract and table of contents only. The complete thesis in print form is available from the University of Adelaide Library. / In mice and other mammalian species, deposition of semen into the female reproductive tract elicits a local inflammatory response. Whether a comparable response occurs within the human cervix has not previously been studied. The experiments described in this thesis demonstrate, using cervical tissue biopsies taken before and after intercourse, that exposure to semen elicits an infiltration of leukocytes into the cervical tissue of peri-ovulatory women. Immunohistochemical analysis identified macrophages and dendritic cells as the predominant leukocytes recruited into the cervical epithelium and stroma following intercourse. Cytotoxic / suppressor T lymphocytes and memory T cells were also increased. Comparable responses were not detected following condom-protected intercourse. Quantitative real-time PCR was performed on duplicate tissue biopsies to investigate the molecular regulation of this response. Expression of GM-CSF, a potent stimulator of myeloid cell recruitment, was found to increase by 2.5-fold following unprotected intercourse. Trends towards increased IL-6 and IL-8 mRNA were also observed. Condom-protected intercourse did not activate cytokine expression, further suggesting that exposure to semen, as opposed to mechanical trauma, provides the inflammatory stimulus. In an in vitro model using the immortalised Ect-1 cell line, TGFβ was identified as a candidate active seminal factor. All three TGFβ isoforms were capable of mimicking the stimulatory ability of seminal plasma in Ect-1 cells and were comparable in their capacity to stimulate both GM-CSF and IL-6 expression in a dose-responsive manner. The addition of TGFβ isoform-specific neutralising antibodies inhibited seminal plasma-induced increases in these cytokines. However TGFβ was unable to stimulate IL-8 production. Addition of IFNƴ was found to strongly inhibit TGFβ-stimulated GM-CSF production, and 19-0H PGE₁ was found to increase IL-6 and IL-8, but not GM-CSF production. Responses to seminal plasma constituents were almost exactly replicated in primary cultures of human ectocervical cells. These results identify TGFβ as the major active constituent in human seminal plasma and indicate that other seminal agents, 19-0H PGE₁ and IFNƴ, interact with TGFβ to differentially regulate cervical cytokine expression. Finally, whether human seminal plasma cytokine content was associated with fertility in men was examined. No relationship between seminal plasma TGFβ₁, TGFβ₂, TGFβ₃, IL-8 or bacterial endotoxin content and fertility status was observed. However, there was an increased likelihood of high IFNƴ content in the male partners of couples experiencing infertility, most notable in recurrent miscarriage. The discriminating value of IFNƴ was increased when evaluated as a ratio of total TGFβ content. Inflammatory changes after exposure of the female reproductive tract to seminal plasma are implicated in 'conditioning' the maternal immune response, to facilitate successful embryo implantation and pregnancy. The studies described in this thesis provide a mechanistic basis for the observations linking exposure to semen with pregnancy success in humans and have expanded our knowledge of the cellular and molecular events that occur within the female reproductive tract following intercourse. Seminal plasma can therefore no longer be thought of as merely a transport medium for spermatozoa, rather as a means for communication between the male and female reproductive tissues, potentially required for optimal pregnancy success. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1213820 / Thesis (Ph.D.) -- University of Adelaide, Medical School, 2005