IL-12 family cytokines IL-23 and IL-27 play an important role linking innate and adaptive immunity, and regulating T-cell responses. The production of IL-12, a structurally similar cytokine, is decreased in chronic HIV infection; therefore IL-23 and IL-27 may also be influenced by HIV infection. I hypothesized that HIV inhibits LPS-induced IL-23 and IL-27 production in human MDMs by suppressing the activation of signalling pathways regulating their expression. In vitro HIV-infection of MDMs did not have any effect on basal secretion of IL-23 or IL-27; however, HIV inhibited LPS-induced production of IL-12/23 p40 and IL-23 p19, and IL-27 EBI3 and IL-27 p28 mRNA expression, and IL-23, IL-12/23 p40 and IL-27 secretion. In order to evaluate the molecular mechanisms by which HIV inhibits IL-23 and IL-27 in LPS-stimulated MDMs, the signalling pathways regulating their expression were evaluated. The PI3K, p38 MAPK, and JNK MAPK pathways were found to positively regulate LPS-induced IL-27 secretion. Interestingly, in vitro HIV infection inhibited LPS-induced p38 and JNK MAPK activation in MDMs. In summary, I have shown that HIV inhibits IL-23 and IL-27 production in LPS-stimulated MDMs and that HIV may inhibit LPS-induced IL-27 production through the inhibition of p38 and JNK MAPK activation. It is currently unknown whether PKCs regulate LPS-induced IL-23 or IL-27 in human monocytes/macrophages. I demonstrated that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 secretion within THP-1 cells, primary monocytes, and MDMs. Classical PKCs were found to positively regulate LPS-induced IL-12/23 p40 and IL-27 p28 mRNA expression and IL-12/23 p40, IL-23, and IL-27 secretion in primary human monocytes. Similarly, the classical PKCs were found to positively regulate IL-27 p28 mRNA expression and IL-27 secretion in THP-1 cells. However, classical PKCs did not regulate LPS-induced IL-27 production in MDMs, or LPS-induced IL-23 production in THP-1 cells. Overall, this demonstrates that classical PKCs differentially regulate LPS-induced IL-23 and IL-27 production in different myeloid cells.

<p>Concurrent with the global escalation of the AIDS pandemic, cryptococcal infections are increasing and are of significant medical importance. Although improvements in antifungal therapy have advanced the treatment of cryptococcosis, the mortality rate is approximately 12% in medically advanced countries, and approaches 50% in less developed regions. Additionally, <italic>C. neoformans</italic> can cause infection in seemingly healthy individuals, elevating its status as a primary human pathogen. Although numerous studies have examined virulence properties, less is understood regarding host immune factors in the lungs during early stages of fungal infection. In the present thesis studies, I examined the roles played by pulmonary surfactant proteins in response to <italic>C. neoformans in vitro</italic> and <italic>in vivo</italic>. We demonstrate that SP-D, but not SP-A, binds to the yeast and increases phagocytosis of poorly encapsulated yeast cells by macrophages, yet concomitantly protects the pathogenic microbes from macrophage-mediated defense mechanisms. Furthermore, we show that SP-D functions as risk factor in vivo</italic> by protecting the yeast cells against oxidant species and thus facilitating disease progression. The results of these studies provide a new paradigm on the role played by surfactant protein D during host responses to <italic>C. neoformans</italic> and, consequently, impart insight into potential future treatment strategies for cryptococcosis.</p> / Dissertation

Although medical devices and biomaterial implants are used clinically in a variety of applications, the process of implanting them damages local tissue and initiates a localized non-specific inflammatory response that is detrimental to device performance. Extensive research efforts have focused on developing material surface treatments and systems to deliver anti-inflammatory agents to abrogate such biomaterial-mediated inflammation, yet long-term use of these traditional materials in vivo is limited due to continued inflammation and fibrous encapsulation. This work aims to address these limitations by developing a versatile implant coating with non-fouling properties using a system based on hydrogel microparticles (i.e. microgels). The overall objective of this project was to evaluate host responses to these microgel coatings. Microgel particles were synthesized from poly(N-isopropyl acrylamide) cross-linked with poly(ethylene glycol)-diacrylate and were successfully deposited onto polymeric substrates using a simple and reproducible spin coating technique. We determined that microgel-coated samples adsorbed significantly lower levels of human fibrinogen than controls. Further characterization using an in vitro culture system demonstrated that microgel coatings significantly reduced the adhesion and spreading of murine macrophages and primary human blood-derived monocytes compared to controls. Materials were then evaluated for early cellular responses following implantation in the intraperitoneal cavity of mice to model acute inflammation. Analyses of explanted biomaterials using immunofluorescence staining techniques revealed that microgel-coated samples significantly reduced the density of surface-adherent cells. Additional analysis using flow cytometry revealed that microgel-coated samples exhibited significantly lower levels of pro-inflammatory cytokines in adherent leukocytes compared to controls, indicating that these coatings modulate cellular pro-inflammatory activities. Finally, we implanted samples subcutaneously in rats to determine the efficacy of microgel coatings at longer time points using an established model of chronic inflammation. Explants were processed histologically and stained for various markers. Importantly, staining demonstrated that the microgel coatings significantly reduced fibrous capsule thickness, the capsules appeared less compact and structurally ordered than controls, and also contained significantly fewer cells. Collectively, these results demonstrate that microgel particles can be applied as polymeric coatings to modulate inflammation and achieve more desirable host responses in vivo, with the potential to extend implant lifetime.

Dengue, a group of four similar viruses transmitted through the bite of a mosquito, is estimated to infect upwards of 100 million annually in over 100 nations throughout the global equatorial belt. Distribution of global dengue is highly skewed as Southeast Asian and Western Pacific regions endure 75% of the global dengue burden. Similar to other regional countries, Malaysia has been rapidly urbanizing, which has supported a hyperendemic dengue state. The biological pathway by which dengue infection causes a wide range of clinical manifestations, spanning asymptomatic to life-threatening severe complications, is not comprehensively understood. Historically, severe dengue complications have primarily occurred in children. Consequentially, the majority of the dengue biological pathway research has been conducted on children; however, extrapolation of research findings to adults may be inappropriate as dengue manifestations have differed between age groups. As developing countries undergo epidemiologic transitions and dengue continues to spread geographically to non-endemic regions, youth and adult populations have been subjected to more of the severe dengue burden. Epidemiology and laboratory-based evidence has supported both memory T-cell and antibody independent enhancement hypotheses to explain the biological pathway of severe dengue. Both hypotheses employ the central idea that a primary infection alters immune components so that during a secondary heterotypic dengue infection, an individual is more at risk for severe complications. Monocytes, immune cells that are pivotal in both hypotheses, have been highly examined through in vivo and in vitro experimentation; however, epidemiological evidence for monocyte involvement is incomplete. The primary objective of the study was to examine if a difference in absolute monocyte count, considering independent risk factors, is present in individuals with primary and secondary dengue infections. A secondary dengue infection was found to raise absolute monocyte count during the defervescence phase of dengue illness in individuals aged 15 years and older 0.71 ± 0.15 (x10^9) compared to those experiencing primary dengue infection. Gender and distance of study participants' residences from Hospital Ampang were found to be risk factors for the relationship of interest; whereas, age and race were not found to be significant risk factors. The study helps expand current knowledge of the severe dengue biological pathway with respect to immunological differences between primary and secondary dengue infections. Further research is needed to confirm and expand the findings of this initial study, specifically to include infecting dengue serotype, education, and socioeconomic status which are known dengue risk factors.

No description available.

The effects of peptides derived from β-lactoglobulin and α-lactalbumin on metabolic syndrome were studied. α-lactalbumin and β-lactoglobulin were hydrolyzed with trypsin, alcalase, flavourzyme, or a combination of alcalase and flavourzyme and fractionated. Angiotensin coverting enzyme inhibition of the < 1 kDa fraction of alcalase hydrolyzed β-lactoglobulin was 95 %. Antioxidant activity of the < 1 kDa fraction of β-lactoglobulin hydrolyzed with a combination of alcalase and flavourzyme was 18 %. Stimulated adipocytes incubated with the < 1 kDa fraction of β-lactoglobulin hydrolyzed with either trypsin or alcalase produced 30 pg/mL of interleukin 6. Adiponectin and glucose transporter type 4 secretions increased 1.1 and 0.86 fold respectively during incubation with the < 1 kDa fraction of β-lactoglobulin hydrolyzed with a combination of alcalase and flavourzyme. Results indicate that β-lactoglobulin peptides formed with alcalase and a combination of alcalase and flavourzyme influence markers associated with metabolic syndrome and may be useful as functional foods or nutraceuticals.

The effects of peptides derived from β-lactoglobulin and α-lactalbumin on metabolic syndrome were studied. α-lactalbumin and β-lactoglobulin were hydrolyzed with trypsin, alcalase, flavourzyme, or a combination of alcalase and flavourzyme and fractionated. Angiotensin coverting enzyme inhibition of the < 1 kDa fraction of alcalase hydrolyzed β-lactoglobulin was 95 %. Antioxidant activity of the < 1 kDa fraction of β-lactoglobulin hydrolyzed with a combination of alcalase and flavourzyme was 18 %. Stimulated adipocytes incubated with the < 1 kDa fraction of β-lactoglobulin hydrolyzed with either trypsin or alcalase produced 30 pg/mL of interleukin 6. Adiponectin and glucose transporter type 4 secretions increased 1.1 and 0.86 fold respectively during incubation with the < 1 kDa fraction of β-lactoglobulin hydrolyzed with a combination of alcalase and flavourzyme. Results indicate that β-lactoglobulin peptides formed with alcalase and a combination of alcalase and flavourzyme influence markers associated with metabolic syndrome and may be useful as functional foods or nutraceuticals.

Heat shock protein (HSP)27 is traditionally described as an intracellular chaperone and signaling molecule, but growing evidence suggests it is released from immune cells where it plays an anti-inflammatory role during atherogenesis. Previously, the O’Brien lab found that overexpression of HSP27 led to augmented HSP27 serum levels in female apolipoprotein E knockout (ApoE-/-) mice, attenuated atherogenesis, and inhibited macrophage foam cell formation via physical binding with scavenger receptor (SR)-A. However, the precise mechanism of atheroprotection remained elusive. This thesis sought to ascertain the mechanism(s) by which HSP27 prevents foam cell formation, and determine if SR-A, a key receptor involved in the uptake of lipid into macrophages, plays an important role in HSP27-mediated atheroprotection. Pre-treatment of human macrophages with recombinant HSP27 (rHSP27) inhibited acytelated low density lipoprotein (acLDL) binding and uptake independent from receptor competition effect. Reduction in uptake was associated with attenuation of expression of SR-A mRNA, total protein, and cell surface expression. To explore the signaling mechanism by which HSP27 modulated SR-A expression it was hypothesized that nuclear factor-kappa B (NF-kB), a major regulator of many atherosclerosis gene programs, is altered by extracellular HSP27. Indeed, rHSP27 markedly activated NF-kB signaling in macrophages. Using an inhibitor of NF-kBsignaling there was an attenuation of rHSP27-induced inhibition of SR-A gene and protein expression, as well as lipid uptake, suggesting that SR-A expression is regulated by NF-kB activation. Lastly, to investigate if SR-A is required for HSP27-mediated atheroprotection in vivo, ApoE-/- and ApoE-/-SR-A-/- mice fed a high fat diet were treated with rHSP25, the mouse orthologue of HSP27, or PBS for 3 weeks. While rHSP25 therapy equally reduced serum cholesterol levels in the mouse cohorts, aortic atherogenesis, assessed using en face and sinus cross-sectional analyses, was attenuated in ApoE-/- mice but not ApoE-/-SR-A-/- mice. In conclusion, rHSP27 inhibits foam cell formation by downregulating SR-A expression. This effect may be associated with NF-kB activation. Reductions in atherosclerotic burden by rHSP27 require SR-A, and are independent of changes in serum cholesterol levels, highlighting the importance of macrophage lipid uptake in atherogenesis. Results presented in this thesis demonstrate that SR-A is a major target for HSP27 atheroprotection in the vessel wall, and provide an impetus for further studies that investigate the potential therapeutic value of HSP27.

Typescript (Photocopy) / Bibliography: leaves 170-198. / xx, 198 leaves, 1 leaf of col. plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1991

Bibliography: leaves 175-203. / xxix, 203 leaves, [14] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates whether cytokines influence the development of the embryo prior to implantation. / Thesis (Ph.D.)--University of Adelaide, Depts. of Obstetrics and Gynaecology and Microbiology and Immunology, 1993