Molecular Markers of Pancreatic β-cell Death
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Open Access
Type
ThesisThesis type
Doctor of PhilosophyAuthor/s
Farr, RyanAbstract
Abstract Loss of insulin-producing β-cells is central to the development of Type 1 diabetes (T1D). Currently, we lack diagnostic tools to quantitate this β-cell loss. Non-protein coding RNAs called microRNAs (miRNAs/miRs) play an important role in islet development and function. ...
See moreAbstract Loss of insulin-producing β-cells is central to the development of Type 1 diabetes (T1D). Currently, we lack diagnostic tools to quantitate this β-cell loss. Non-protein coding RNAs called microRNAs (miRNAs/miRs) play an important role in islet development and function. Recent detection of miRNAs in peripheral circulation, has renewed interest in microRNA biomarkers of diabetes. Comparably, circulating insulin cell-free (cf)DNA has been proposed as a direct biomarker of β-cell death. DNA methylation studies have identified specific sites within DNA that are unmethylated in β-cells but methylated in other cell types, thus providing a handle to discriminate between cfDNA from β-/non-β-cells. Previous research carried out in the Hardikar lab identified a signature of 20 miRNAs (the ‘RAPID’ signature) with potential as a biomarker of β-cell death. The RAPID signature was revised to accommodate other microRNAs finally constituting a panel of 50 microRNAs (PREDICT T1D panel). An analysis of these 50 miRNAs, as well as insulin cfDNA in serum/plasma from individuals before, during and after clinical diagnosis of T1D is presented. Human islet cell death assays using sodium nitroprusside exposure identified a subset of 27 miRNAs and insulin cfDNA associated with islet cell stress/death. Non-obese diabetic mice (N=32) were found to have elevated candidate miRNAs prior to immune infiltration and glycaemic dysfunction. This trend was also noted in the human progression to T1D; 26 miRNAs were elevated in (N=19) high-risk individuals and those at diagnosis (N=199) but decreased within 6-weeks after diagnosis. Furthermore, candidate miRNAs exhibited differential abundance with disease duration, residual C-peptide, and microvascular complications in 180 subjects with prolonged T1D. At diagnosis, miRNAs and cfDNA associated with GAD III autoantibody titres (N=167 P-values range from 0.044 to <0.0001) and HbA1c levels (N=187, P-values range from 0.047 to 0.00095). Such biomarkers may inform medical researchers as to how to predict the development of T1D, monitor response to interventions such as islet transplantation, vaccines & drugs aiming to retard β-cell loss. In basic research, such an assay may help to select treatments to block β-cell death and guide the development of new treatments to lessen the burden of diabetes.
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See moreAbstract Loss of insulin-producing β-cells is central to the development of Type 1 diabetes (T1D). Currently, we lack diagnostic tools to quantitate this β-cell loss. Non-protein coding RNAs called microRNAs (miRNAs/miRs) play an important role in islet development and function. Recent detection of miRNAs in peripheral circulation, has renewed interest in microRNA biomarkers of diabetes. Comparably, circulating insulin cell-free (cf)DNA has been proposed as a direct biomarker of β-cell death. DNA methylation studies have identified specific sites within DNA that are unmethylated in β-cells but methylated in other cell types, thus providing a handle to discriminate between cfDNA from β-/non-β-cells. Previous research carried out in the Hardikar lab identified a signature of 20 miRNAs (the ‘RAPID’ signature) with potential as a biomarker of β-cell death. The RAPID signature was revised to accommodate other microRNAs finally constituting a panel of 50 microRNAs (PREDICT T1D panel). An analysis of these 50 miRNAs, as well as insulin cfDNA in serum/plasma from individuals before, during and after clinical diagnosis of T1D is presented. Human islet cell death assays using sodium nitroprusside exposure identified a subset of 27 miRNAs and insulin cfDNA associated with islet cell stress/death. Non-obese diabetic mice (N=32) were found to have elevated candidate miRNAs prior to immune infiltration and glycaemic dysfunction. This trend was also noted in the human progression to T1D; 26 miRNAs were elevated in (N=19) high-risk individuals and those at diagnosis (N=199) but decreased within 6-weeks after diagnosis. Furthermore, candidate miRNAs exhibited differential abundance with disease duration, residual C-peptide, and microvascular complications in 180 subjects with prolonged T1D. At diagnosis, miRNAs and cfDNA associated with GAD III autoantibody titres (N=167 P-values range from 0.044 to <0.0001) and HbA1c levels (N=187, P-values range from 0.047 to 0.00095). Such biomarkers may inform medical researchers as to how to predict the development of T1D, monitor response to interventions such as islet transplantation, vaccines & drugs aiming to retard β-cell loss. In basic research, such an assay may help to select treatments to block β-cell death and guide the development of new treatments to lessen the burden of diabetes.
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Date
2017-04-24Licence
The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.Faculty/School
Sydney Medical SchoolDepartment, Discipline or Centre
NHMRC Clinical Trials CentreAwarding institution
The University of SydneyShare