Adipose tissue inflammation is characterised by increased infiltration of macrophages and is associated with a marked increase in the synthesis and release of proinflammatory factors such as TNFα, IL-6 and MCP-1. Studies suggest that these chemokines and cytokines contribute to local tissue inflammation and levels of inflammatory mediators in the systemic circulation. The potential role of the vitamin D receptor in modulating inflammation in obesity has received increasing attention, with evidence suggesting that 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has potent immunoregulatory effects. The data presented in this thesis showed adipose tissue expresses the vitamin D receptor, along with vitamin D metabolising enzymes CYP27B1 and CYP24A1. Treatment of adipocytes with 1,25(OH)2D3 reduced the secretion of key cytokines and chemokines involved in the inflammatory response induced by macrophage-secreted factors. MCP-1, IL-6, IL-8 and RANTES production by human adipocytes was significantly downregulated, and western blotting data supports that this was due to the inhibitory effects of 1,25(OH)2D3 on the NF-κB and MAPK signalling pathways. Treatment with 1,25(OH)2D3 also abolished macrophage-induced activation of NFκB, increasing IκBα expression and reducing NFκB p65 phosphorylation. Mitogen-activated protein kinase (MAPK) signalling activated by MC medium was also inhibited by 1,25(OH)2D3 , reducing phosphorylated p38 MAPK and phosphorylated Erk1/2. Investigations into its downstream effects showed 1,25(OH)2D3 decreased macrophage-induced inflammatory cytokine expression, reducing IL-8, MCP-1, RANTES and IL-6. To confirm the involvement of the vitamin D receptor in modulating the inflammatory response in adipocytes, two 1,25(OH)2D3 analogues, ZK159222 and ZK191784, were investigated for its effects on adipocyte-macrophage crosstalk. The anti-inflammatory effects of ZK159222 and ZK191784 are demonstrated for the first time in human adipocytes. ZK159222 treatment increased IκBα in adipocytes stimulated with macrophage-conditioned medium. In contrast, ZK159222 markedly reduced protein expression of phos-NF-κB p65. In studies of MAPK activation, ZK159222 dose-dependently decreased expression of phosphorylated p38 MAPK. ZK191784 treatment was observed to increase IκBα while reduce phosphorylated NF-κB p65 levels compared to vehicle controls. ZK191784 also showed an inhibitory effect on protein expression of phosphorylated p38 MAPK. In addition, both 1,25(OH)2D3 analogues reduced protein secretion of MCP-1 and IL-6 by human adipocytes. Both compounds also significantly reduced IL-8 expression compared to vehicle controls as well as 1,25(OH)2D3 treatment as well as MC-induced RANTES expression. Overall this research demonstrates that vitamin D3 has anti-inflammatory properties in human adipocytes, probably mediated by inhibition of the NFκB and MAPK signalling pathways. Reviewing the current evidence, the data suggests that targeting the vitamin D signalling system in adipose tissue presents a novel approach for modulating adipose tissue function, and in particular, ameliorating inflammation perpetuated by macrophage-adipocyte crosstalk in obesity.

No description available.

No description available.

Part one of this volume presents a review of the literature on the relationship between chronic pain and socioeconomic status. It examines the evidence supporting the association and considers the psychological meaning of the findings. Part two consists of a qualitative empirical paper which samples patients with chronic orofacial pain to explore their understanding of their pain and their beliefs and fears about the causes and maintenance of their pain, both before and after an initial consultation at a specialist pain clinic. The final section is a critical appraisal of conducting this thesis. It contains a personal reflection of conducting both the literature review and empirical paper and describes some of the obstacles encountered during the process.

No description available.

No description available.

The widespread roll-out of antiretroviral therapy (ART) has resulted in a decline of HIV-related deaths; as a result the HIV positive population is rapidly ageing with improved survival of HIV positive adults on ART. In sub-Saharan Africa, including South Africa, where older adults comprise a significant proportion of the total population, health services face the complexities of an ageing population and HIV. The aim of this PhD study is to inform understanding of issues relating to older adults, aged 50 years or more, HIV infection and ART, who are resident in Northern KwaZulu-Natal, South Africa. Data from the cross-sectional Wellbeing of Older People Study (WOPS), including 422 older adults and nested within the demographic surveillance system, show that HIV positive older adults receiving ART for >1 year had less chronic morbidity than HIV negative older adults despite having higher IL6 and hsCRP levels. To quantify the cause-specific morbidity burden at the time of initiating ART, data on 1 409 adults aged ≥16 years obtained from the ART Clinical Cohort show that chronic morbidity at time of ART initiation burden and HIV-associated morbidity was more common in older than younger (16-49 years old) adults. Data from the HIV Treatment and Care programme, linked to an electronic Hospital Information database (n=8598 adults aged ≥16 years) show that older adults had a lower hospitalisation rate, but higher case fatality rates, than younger adults. In the HIV treatment and Care programme, including 8846 overall, in the first year of ART, mortality was higher in older than younger adults, but rates in the two groups were similar thereafter. Older adults had a blunted immunological but superior virological response. All-cause mortality risk increased with a decline in CD4 cell count and unsuppressed viral load. Further detailed data from the ART Clinical Cohort showed that, in both age groups, the contribution of multiple co-morbidity to early mortality was high. The results presented here contribute towards evidence required to understand issues surrounding the health of older adults in the context of high HIV prevalence and incidence with widespread availability and access to ART and provide knowledge required for evidence-based health planning for the ageing HIV cohort. The thesis concludes with a discussion of the implications for health service development and future research.

The prognosis of those infected with HIV-1 has improved significantly since the introduction of highly active antiretroviral therapy (HAART). This has led to complete suppression of HIV-1 replication and reduction of viraemia to undetectable levels. Initially HAART comprised of three classes of drugs, namely nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs), which target two important viral enzymes. Until recently, patients developing highly drug-resistant HIV-1 have had limited therapy options. This has changed in the last few years with the development and approval for use of second-generation NNRTIs and PIs, and three new classes of drugs including integrase strand transfer inhibitors (INSTIs). This means that patients undergoing INSTI-containing salvage therapy are taking drugs targeting all three HIV-1 pol genes; protease (PR), RT and IN. However, little data is available on the evolution, interaction and linkage of drug resistance mutations throughout the pol gene. In this study, we developed a single genome sequencing assay of the full-length HIV-1 pol gene and used it to investigate the development and linkage of drug resistance mutations in sequential samples from two patients failing INSTI-containing salvage therapy. Different phylogenetic methods were used to explore the evolution and dynamics of drug resistance mutations in the full-length HIV-1 pol gene. Furthermore, we examined the effect of co-evolved PR and RT on the susceptibility of patient-derived viruses to INSTIs and viral replicative fitness. Our data indicate that the development of drug resistance mutations in IN is complex and is a fine balance between attaining high levels of drug resistance and decent replicative fitness. This is to a degree influenced by mutations in other regions of the HIV-1 pol gene. Taken together, the data suggests that larger regions of patient-derived HIV-1 genome should be examined in order to get a good understanding of HIV-1 drug susceptibility.

In this study M-CSF differentiated human monocyte derived macrophages were used to investigate HIV-1 interactions with macrophage innate immune responses. Macrophages may be an important host cell for HIV-1. HIV-1 can infect and replicate within these cells without causing host cell cytopathicity unlike in T cells. Macrophages also aid in the spread of the virus and are likely to act as a viral reservoir protected from antivirals and immune responses due to the unique localisation of the virus within these cells. Surprisingly HIV-1 infection has little effect on the steady state transcriptome of MDM and despite the role of macrophages to detect incoming pathogens; no innate immune response to HIV-1 could be detected, in contrast with other viruses tested. The lack of immune response was not due to active viral suppression and addition of exogenous IFN or activation of the innate immune response at the time of HIV-1 infection can restrict viral infection in these cells, despite HIV-1 having a full complement of accessory proteins known to counteract IFN inducible restriction factors. This HIV-1 restriction induced by IFN was long lasting, likely for the lifetime of the MDM. IFN treatment of MDM with established HIV-1 infection however only transiently suppressed viral replication. Comparisons of MDM with other cell types which do show an innate immune IFN response to HIV-1 showed that MDM have relatively low levels of TLR7 gene expression, suggesting that MDM may lack one of the PRRs for detecting HIV-1. HIV-1 infection of MDM was found to attenuate NFκB activation in response to TLR stimulation and this attenuation could be reversed by priming the MDM with IFNγ. However this attenuation of the NFκB signal did not translate into decreased protein expression for a selection of proinflammatory cytokines examined.

Bayesian Model Selection Approaches are flexible methods that can be utilised to investigate Genetic Association studies in greater detail; enabling us to more accurately pin-point locations of disease genes in complex regions such as the MHC, as well as investigate possible causal pathways between genes, disease and intermediate phenotypes. This thesis is split into two distinct parts. The first uses a Bayesian Multivariate Adaptive Regression Spline Model to search across many highly correlated variants to try to determine which are likely to be the truly causal variants within complex genetic regions and also how each of these variants influences disease status. Specifically, I consider the role of genetic variants within the MHC region on SLE. The second part of the thesis aims to model possible disease pathways between genes, disease, intermediate phenotypes and environmental factors using Bayesian Networks, in particular focussing upon Coronary Heart disease and numerous blood biomarkers and related genes. Bayesian Multivariate Adaptive Regression Spline Model: Genetic association studies have the problem that often many genotypes in strong linkage disequilibrium (LD) are found to be associated with the outcome of interest. This makes it difficult to establish the actual SNP responsible. The aim of this part of the thesis is to investigate Bayesian variable selection methods in regions of high LD. In particular, to investigate SNPs in the major histocompatibility complex (MHC) region associated with systematic lupus erythematosus (SLE). Past studies have found several SNPs in this region to be highly associated with SLE but these SNPs are in high LD with one another. It is desirable to search over all possible regression models in order to find those SNPs that are most important in the prediction of SLE. The Bayesian Multivariate Adapative Regression Splines (BMARS) model used should automatically correct for nearby associated SNPs, and only those directly associated should be included in the model. The BMARS approach will also automatically select the most appropriate disease model for each directly associated variant. It was found that there appear to be 3 separate SNP signals in the MHC region that show association with SLE. The rest of the associations found using simple Frequentist tests are likely to be due to LD with the true signal. Bayesian Networks for Genetic Association Studies: Coronary Heart Disease (CHD) is one of many diseases that result from complicated relationships between both genetic and environmental factors. Identifying causal factors and developing new treatments that target these factors is very difficult. Changes in intermediate phenotypes, or biomarkers, could suggest potential causal pathways, although these have a tendency to group amongst those patients with higher risk of CHD making to difficult to distinguish independent causal relationships. I aim to model disease pathways allowing for intermediate phenotypes as well as genetic and environmental factors. Statistical methodology was developed using directed acyclic graphs (DAGs). Disease outcomes, genes, intermediate phenotypes and possible explanatory variables were represented as nodes in a DAG. Possible models were investigated using Bayesian regression models, based upon the underlying DAG, in a reversible jump MCMC framework. Modelling the data this way allows us to distinguish between direct and indirect effects as well as explore possible directionality of relationships. Since different DAGs can belong to the same equivalence class, some directions of association may become indistinguishable and I am interested in the implications of this. I investigated the integrated associations of genotypes with multiple blood biomarkers linked to CHD risk, focusing particularly on relationships between APOE, CETP and APOB genotypes; HDL- and LDL- cholesterol, triglycerides, C-reactive protein, fibrogen and apolipoproteins A and B. Overview: I will begin by introducing the topics of genetics, statistics and directed acyclic graphs with a background on each (Chapters 2,3 and 4 respectively). Chapter 5 will then detail the analysis and results of the BMARS model. The analysis and results of Bayesian networks for genetic association studies will then be covered in Chapter 6.