CD4 + T cells can actively kill b-cells in type I diabetes as well as help CD8 + T cells become cytolytic. Cytokines have the potential to kill b-cells, or upregulate Fas on b-cells, and increase their susceptibility to FasL. We investigated the direct effects of cytokines on b-cells in perforin-deficient non-obese diabetic (NOD) mice and NOD4.1 TCR transgenic mice, two models in which CD8 + T cells play a less dominant role. Inhibiting the effects of cytokines by the overexpression of suppressor of cytokine signalling-1 (SOCS1) in b-cells did not reduce diabetes or insulitis in perforin-deficient NOD, NOD4.1 or interleukin (IL)-1 receptor-deficient NOD4.1 mice. SOCS1 overexpression prevented Fas upregulation on NOD4.1 b-cells, but did not prevent islet destruction because SOCS1 transgenic islets were killed when grafted into NOD4.1.scid mice. Likewise, Fas-deficient NOD.lpr islets were destroyed in NOD4. In both humans and the non-obese diabetic (NOD) mice, type I diabetes (T1D) is characterized by accumulation of inflammatory cells including macrophages, dendritic cells, B cells, CD4 + and CD8 + T cells. 1 Of these, it is widely accepted that autoreactive CD4 + and CD8 + T cells play a major role in disease development and there is evidence for a role for all of these cell types.In adoptive transfer studies, both CD4 + and CD8 + T cells from pre-diabetic NOD mice are required to transfer diabetes into immunodeficient mice. 2 T1D does not develop in the absence of CD8 + T cells 3-6 and NOD mice deficient in perforin, a major constituent of the cytotoxic granules of CD8 + T cells that have a significantly reduced incidence of T1D, 7,8 suggesting that CD8 + T cells play a dominant role in the effector phase of T1D. However, some perforin-deficient NOD mice develop diabetes, as do some 'beta-bald' NOD mice in which class I major histocompatibility complex is not expressed on b-cells. 9 Also, b-cell destruction appears eventually to become CD8 independent in NOD mice, with anti-CD8 antibody therapy becoming insufficient to block disease as mice get older, 10 or in disease recurrence when syngeneic b-cells are transplanted into diabetic NOD mice. The residual diabetes in these models is likely to be due to CD4 + T cells. Activated CD4 + T cells from pre-diabetic mice can transfer diabetes 2,11 and clones of b-cell-specific CD4 + T cells such as NOD4.1 12 and BDC2.5. 13 cause diabetes without the help of CD8 + T cells. Earlier studies suggest that CD4 + T cells cause destruction indirectly through cytokines that can either directly kill b-cells or recruit other effector cells such as CD8 + T cells and macrophages. [14][15][16] In vitro, cytokine combinations of interleukin (IL)-1b and interferon (IFN)g can cause b-cell death through pathways involving production of reactive nitrogen and oxygen species. 17 Despite this in vitro toxicity, the absence of IL-1R or IFNgR in vivo has little or no effect on diabetes incidence in NOD mice. [18][19][20] This suggests that if these cytokines are involved in b-cell death, their...

This study has identified a low prevalence of high-risk HPV in Queensland, Australia.

A significant proportion of mucosal squamous cell carcinomas of the head and neck (HNSCC; particularly of the oropharynx) are directly attributable to the human papillomavirus (HPV). The increase in the incidence of HPV-related tumours has been postulated to be due to changing sexual practices in the community. We analysed 136 formalin-fixed paraffin-embedded squamous cell carcinomas from the oral cavity (n=40) and oropharynx (n=96) recruited from the Princess Alexandra Hospital (Brisbane, Australia). Samples were analysed for the presence of HPV DNA using a combination of mucosal HPV general primer GP+ PCR and sequencing; p expression was assessed by immunohistochemistry. Each patient completed a questionnaire detailing their lifestyle factors, such as tobacco smoking and alcohol consumption, marital status, and sexual behaviour and history. The HPV DNA prevalence was 5 % in the oral cavity cancers and 72 % in the oropharyngeal cancers (P<0.0001). HPV-16 was the most commonly detected HPV type (found in 91 % of all HPV-positive tumours). There was a strong correlation between HPV DNA positivity and positive p16 staining in oropharyngeal tumours (P<0.0001). Having an HPV-related tumour was associated with being married or having been married previously (P=0.046), an increasing number of passionate kissing partners (P=0.046), ever having given oral sex (P=0.0007) and an increasing number of oral sex partners (P=0.0015). This study found a higher prevalence of HPV in oropharyngeal compared to oral cavity tumours, with a strong association being identified between oral sex behaviours and HPV-positive tumours. Further research is needed to establish that vaccines will reduce the transmission and carriage of oropharyngeal HPV infections.

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Squamous cell carcinoma of mucosal sites in the head and neck (HNSCC) is the sixth most common cause of cancer worldwide, and despite advances in conventional management, it still has significant morbidity and mortality associated with both diagnosis and treatment. Advances in our understanding of the biological mechanisms underlying this disease have demonstrated a significant difference between human papillomavirus (HPV)-associated, HPV and tobacco associated, and HPV-negative disease. It remains important to further elucidate the biologic and genetic differences between HPV-associated and tobacco-associated disease, with the aim of earlier diagnosis through screening, and advances in management including the development of novel therapeutic agents. MicroRNAs (miRNAs) are small, non-coding RNAs that function as post-transcriptional regulators of gene expression, and have effects on almost every cellular function, and have potentially important applications to diagnosis, management and prognosis in HNSCC. Establishing a cellular miRNA expression profile for HPV-associated disease may therefore have important implications for the screening and treatment of this disease. This review summarises the current findings regarding miRNA expression in mucosal HNSCC, and focuses particularly on miRNA expression in HPV-associated tumours.

We found large variations in HPV-16 viral load from 1 to 930 copies per cell (median 34 copies per cell).

Squamous cell carcinoma of mucosal head and neck sites (HNSCC) is the sixth most common cause of cancer world-wide, and is associated with a significant morbidity and mortality despite advances in therapeutic options over the past decades. HNSCC includes tumours of the oral cavity, oropharynx, larynx and hypopharynx. While there has been a decline in tumours occurring as a result of exposure to the traditional risk factors of tobacco smoking and alcohol consumption, a significant increase has been observed in the number of tumours attributed to the Human Papillomavirus (HPV). This has primarily been associated with causation of tumours in the oropharynx, however, a smaller number of tumours at other subsites are also likely to be related to the virus. Although HPV-related tumours tend to have an improved prognosis and a better response to chemo-and radiotherapy, the pathobiology underlying these differences is not yet fully understood.MiRNAs are short, non-coding single strands of RNA which regulate gene expression at the posttranscriptional level. They have been identified to be dysregulated and function as tumour suppressor or oncogenes in a number of human cancers, including head and neck cancers. MiRNAs have also been associated with prognostication including associations with recurrence of disease and diseasefree survival. As they are readily available across a range of body tissues including solid tissue, saliva, and plasma, these biomarkers have potential utility in relation to screening for disease diagnosis, recurrence or progression. Although there is an established difference between HPV-positive and negative tumours in the oropharynx clinically, the majority of studies investigating miRNA expression in HNSCC have not taken this factor into account. In the small number of studies which have examined the effect of HPV on miRNA expression in HNSCC, there is a lack of consistency in the results described.This thesis aimed to assess the difference in miRNA expression between HPV-positive and negative tumours, through use of miRNA microarray followed by validation with real-time PCR using TaqMan assays combined with a sensitive detection method (Fluidigm HD) in a larger cohort of patients. It also investigated differences in miRNA expression in association with lifestyle factors, demographics and clinical outcomes. A set of seven miRNAs was identified to be differentially expressed between HPV-positive and negative tumours in the oropharynx. No difference in miRNA expression was observed between the two tumour cohorts at other subsites in the head and neck.Differences in miRNA expression were also observed with lifestyle factors such as smoking status and alcohol consumption. Recurrence of the primary tumour and overall disease-free survival were further associated with altered miRNA expression. The findings outlined in this thesis add to the present literature regarding differences in miRNA expression between HPV-positive and negative iii tumours in the oropharynx, and provide a basis for further...

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