Non-communicable diseases (NCD) such as cancer, heart disease and cerebrovascular injury are dependent on or aggravated by inflammation. Their prevention and treatment is arguably one of the greatest challenges to medicine in the 21st century. The pleiotropic, proinflammatory cytokine; interleukin-l beta (IL-l~) is a primary, causative messenger of inflammation. Lipopolysaccharide (LPS) induction ofIL-l~ expression via toll-like receptor 4 (TLR4) in myeloid cells is a robust experimental model of inflammation and is driven in large part via p38-MAPK and NF-KB signaling networks. The control of signaling networks involved in IL-l~ expression is distributed and highly complex, so to perturb intracellular networks effectively it is often necessary to modulate several steps simultaneously. However, the number of possible permutations for intervention leads to a combinatorial explosion in the experiments that would have to be performed in a complete analysis. We used a multi-objective evolutionary algorithm (EA) to optimise reagent combinations from a dynamic chemical library of 33 compounds with established or predicted targets in the regulatory network controlling IL-l ~ expression. The EA converged on excellent solutions within 11 generations during which we studied just 550 combinations out of the potential search space of - 9 billion. The top five reagents with the greatest contribution to combinatorial effects throughout the EA were then optimised pair- wise with respect to their concentrations, using an adaptive, dose matrix search protocol. A p38a MAPK inhibitor (30 ± 10% inhibition alone) with either an inhibitor of IKB kinase (12 ± 9 % inhibition alone) or a chelator of poorly liganded iron (19 ± 8 % inhibition alone) yielded synergistic inhibition (59 ± 5 % and 59 ± 4 % respectively, n=7, p≥O.04 for both combinations, tested by one way ANOVA with Tukey's multiple test correction) of macrophage IL-l~ expression. Utilising the above data, in conjunction with the literature, an LPS-directed transcriptional map of IL-l ~ expression was constructed. Transcription factors (TF) targeted by the signaling networks coalesce at precise nucleotide binding elements within the IL-l~ regulatory DNA. Constitutive binding of PU.l and C/EBr-~ TF's are obligate for IL-l~ expression. The findings in this thesis suggest that PU.l and C/EBP-~ TF's form scaffolds facilitating dynamic control exerted by other TF's, as exemplified by c-Jun. Similarly, evidence is emerging that epigenetic factors, such as the hetero-euchromatin balance, are also important in the relative transcriptional efficacy in different cell types. Evolutionary searches provide a powerful and general approach to the discovery of novel combinations of pharmacological agents with potentially greater therapeutic indices than those of single drugs. Similarly, construction of signaling network maps aid the elucidation of pharmacological mechanism and are mandatory precursors to the development of dynamic models. The symbiosis of both approaches has provided further insight into the mechanisms responsible for IL-lβ expression, and reported here provide a - platform for further developments in understanding NCD's dependent on or aggravated by inflammation.

Bibliography: leaves 161-204 / xv, 204 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (M.D.)--University of Adelaide, Dept. of Medicine and Pathology, 1985

Inflammation plays a crucial role in protecting the host from infection and tissue injury. However, uncontrolled inflammation contributes to the pathogenesis of major auto-inflammatory diseases. Interleukin-1 (IL-1), a pleiotropic pro-inflammatory cytokine, is a pivotal mediator of many of these diseases. The best characterised IL-1 family members, IL-1α and IL-1β, are produced as precursor forms of 31 kDa in size. Both precursors are cleaved and secreted, activating transmembrane IL-1 receptors on IL-1-responsive cells. Many studies that focused on IL-1α have shown that the precursor and processed mature Ct peptide, as well as its N terminus (Nt) form, can elicit a signal. However, with IL-1β, only the processed mature Ct form is known to elicit an inflammatory response and no immunological activity has been attributed to Nt fragments of pro-IL-1β. Therefore, the first objective of this study was to produce recombinant human Nt-IL-1β fragments in bacterial and mammalian expression system to investigate their possible immunomodulatory functions. Recombinant His-tagged N-terminus fragments (10 and 14 kDa) of pro-IL-1β were cloned into the bacterial expression vector pET-22(+) and expressed in E. coli BL21(DE3) followed by purification using three consecutive columns (IMAC, SEC and AEC). Purification analysis of eluted proteins from columns indicated that the recombinant proteins were always co-purified with some other bacterial proteins. The Nt fragments of pro-IL-1β were cloned into the mammalian expression plasmid, pcDNA3.1(+). Expression of these proteins was monitored by transfection of two mammalian cell lines: Human Embryonic Kidney (HEK) 293 cells and monkey kidney cells (COS-7). No protein expression was observed with either construct. These limitations urged us to investigate the expression and degradation of endogenous IL-1 in vitro. Previous studies have shown that the transcription of cytokine genes in response to lipopolysaccharide (LPS) is usually rapid and begins to decline within a few hours after stimulation. The proteasome is the major cellular proteolytic apparatus and controls the turn-over of cellular proteins. We investigated the intracellular stability of IL-1α and IL-1β in LPS-stimulated mouse J774 macrophages and primary mouse bone marrow derived macrophages (BMDMs). Exposure of LPS-stimulated J774 and BMDMs to three different classes of proteasome inhibitors (peptide alhedyde (ALLN), peptide boronate (MG262) and non-peptide inhibitor (β-lactone)) prevented the degradation of intracellular IL-1α and IL-1β in a concentration and time dependent manner. Furthermore, the release of IL-1 into the culture media was not affected by any of these inhibitors in LPS-stimulated J774 cells. However, in LPS-stimulated BMDMs, β-lactone increased the release of both IL-1α and IL-1β and ALLN only increased IL-1α release into culture supernatant compared to control. MG262 had no effect on the release of either. These data suggest that the proteasome plays an important role in controlling the amount of IL-1α and IL-1β by restricting the intracellular levels of these cytokines in activated monocytes and macrophages. Therefore, this study provides evidence in support of the hypothesis that the proteasome is involved in the degradation of IL-1α and IL-1β and may offer a potential therapeutic target in inflammatory diseases.

Errata slip inserted / Bibliography: leaves 178-199 / xxi, 199, [55] leaves, [3] leaves of 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 Clinical and Experimental Pharmacology, and Rheumatology Unit, Royal Adelaide Hospital, 1994

Bibliography: leaves 211-260 / xvii, 260 leaves ; 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 Pathology, 1986

Covalent modifications of histone tails play essential roles in mediating chromatin structure and epigenetic regulation. JmjD3 is a JumonjiC domain containing histone demethylase, belongs to the KDM6 subfamily, and catalyses the removal of methyl groups on methylated lysine 27 on histone 3 (H3K27), a critical mark to promote polycomb mediated repression and gene silencing. The importance of JmjD3 has been implicated in development, cancer biology and immunology. In this thesis, I report the recombinant production of active human JmjD3, development of two in vitro screening assays, a cell-based assay, and structural determination of JmjD3 in complex with the inhibitor 8-hydroxy-5-carboxyquinoline (8HQ). A highly selective and potent small molecule inhibitor GSK-J1 was subsequently identified. The inhibitor is active in HeLa cells and promotes a dose-dependent increase of global H3K27 methylation. The inhibitor GSK-J1 was used in two different cell assay systems related to inflammation and differentiation, to understand how H3K27 demethylation controls cellular functions. By inhibiting H3K27me3 demethylation, it is demonstrated that tumor necrosis factor (TNF) and other pro-inflammatory cytokines are regulated by H3K27 demethylase inhibition in M1- type macrophages derived from healthy volunteers and rheumatoid arthritis patients. It is also shown that inhibition of H3K27me3 demethylation abrogates cellular fusion of M2- type macrophages. During RANKL induced osteoclast differentiation, JmjD3 is up-regulated and promotes the expression of the key transcription factor NFATc1. By inhibiting JmjD3, NFATc1 expression is reduced and osteoclastogenesis is inhibited. This mechanism demonstrates a novel anti-resorptive principle of potential utility in conditions of excess bone resorption such as osteoporosis, bone erosion in inflammatory arthritis or cancer of the bone. These experiments further resolve the ambiguity between scaffold and catalytic function associ- ated with the H3K27 demethylase in these biological systems, and demonstrate that its enzymatic activity is crucial for epigenetic regulation of macrophage and osteoclast function.

Nitric oxide (NO) is an important biological molecule within the body, which over production of this molecule in response to different stimulations can cause various inflammatory diseases. Over production of this molecule is caused by the induction of the inducible nitric oxide synthase (iNOS) enzyme. This enzyme uses L-arginine as a substrate and therefore the presence and transport of this amino acid into the cells can be a key factor in regulating NO over production. Different signalling mechanisms have been implicated in the regulation of this pathway and one of which involves the Mitogen Activated Protein Kinases (MAPK). This family of proteins respond to inflammatory conditions and may mediate effects induced by inflammatory mediators. Of the MAPKs, the role of the c-Jun-N-terminal kinase (JNK) pathway in the induction of iNOS is still controversial. JNK and its downstream target, the transcription factor Activator Protein-1 (AP-1), have shown contradictory effects on iNOS induction leading to controversies over their role in regulating iNOS expression in different cell systems or with various stimuli. The studies described in this thesis have determined the role of JNK/AP-1 on iNOS expression, NO production, L-arginine uptake and also on the transporters responsible for L-arginine transport into the cells. The studies were carried out in two different cell types: rat aortic smooth muscle cells (RASMCs) and J774 macrophages which are both critically associated with the over production of NO in vascular inflammatory disease states. The first approach was to block the expression of the inducible L-arginine-NO pathway using SP600125 and JNK Inhibitor VIII which are both pharmacological inhibitors of JNK. The results from these studies showed that the pharmacological intervention was without effect in RASMCs, but inhibited iNOS, NO and L-arginine transport in J774 macrophages. In contrast, the molecular approach employed using two dominant negative constructs of AP-1 (TAM-67 and a-Fos) revealed a different profile of effects in RASMCs, where a-Fos caused an induction in iNOS and NO while TAM-67 had an inhibitory effect on iNOS, NO, L-arginine transport and CAT-2B mRNA expression. The latter was unaffected in RASMCs but suppressed in J774 macrophages by SP600125. Examination of JNK isoforms expression showed the presence of JNK1 and 2 in both cell systems. Moreover, stimulation with LPS/IFN- or LPS alone resulted in JNK phosphorylation which did not reveal any difference between smooth muscle cells and macrophages. In contrast, expression and activation of AP-1 subunits revealed differences between the two cell systems. Activation of cells with LPS and IFN- (RASMCs) or LPS alone (J774 macrophages) resulted in changes in the activated status of the different AP-1 subunit which was different for the two cell systems. In both cell types c-Jun, JunD and Fra-1 were increased and in macrophages, FosB activity was also enhanced. Inhibition of JNK with SP600125 caused down-regulation in c-Jun in both cell types. Interestingly this down-regulation was in parallel with increases in the subunits JunB, JunD, c-Fos and Fra-1 in RASMCs or JunB and Fra-1 in J774 macrophages. Since, SP600125 was able to exert inhibitory effects in the latter cell type but not in RASMCs, it is possible that the compensatory up-regulation of certain AP-1 subunits in the smooth muscle cells may compensate for c-Jun inhibition thereby preventing suppression of iNOS expression. This notion clearly needs to be confirmed but it is potentially likely that hetero-dimers formed between JunB, JunD, c-Fos and Fra-1 could sustain gene transcription in the absence of c-Jun. The precise dimer required has not been addressed but unlikely to exclusively involve JunB and Fra-1 as these are up-regulated in macrophages but did not sustain iNOS, NO or induced L-arginine transport in the presence of SP600125. To further support the argument above, the dominant negatives caused varied effects on the activation of the different subunits. a-Fos down-regulated c-Jun, c-Fos, FosB, Fra-1 whereas TAM-67 reduced c-Jun and c-Fos but marginally induced Fra-1 activity. Associated with these changes was an up-regulation of iNOS-NO by a-Fos and inhibition by TAM-67. Taken together, the data proposes a complex mechanism(s) that regulate the expression of the inducible L-arginine-NO pathway in different cell systems and the complexity may reflect diverse intracellular changes that may be different in each cell type and not always be apparent using one experimental approach especially where this is pharmacological. Moreover, these findings strongly suggest exercising caution when interpreting pure pharmacological findings in cell-based systems particularly where these are inconsistent or contradictory.