Circulating Differentially Methylated Amylin DNA as a Biomarker of β-Cell Loss in Type 1 Diabetes

Abstract

In type 1 diabetes (T1D), β-cell loss is silent during disease progression. Methylation-sensitive quantitative real-time PCR (qPCR) of β-cell-derived DNA in the blood can serve as a biomarker of β-cell death in T1D. Amylin is highly expressed by β-cells in the islet. Here we examined whether demethylated circulating free amylin DNA (cfDNA) may serve as a biomarker of β-cell death in T1D. β cells showed unique methylation patterns within the amylin coding region that were not observed with other tissues. The design and use of methylation-specific primers yielded a strong signal for demethylated amylin in purified DNA from murine islets when compared with other tissues. Similarly, methylation-specific primers detected high levels of demethylated amylin DNA in human islets and enriched human β-cells. In vivo testing of the primers revealed an increase in demethylated amylin cfDNA in sera of non-obese diabetic (NOD) mice during T1D progression and following the development of hyperglycemia. This increase in amylin cfDNA did not mirror the increase in insulin cfDNA, suggesting that amylin cfDNA may detect β-cell loss in serum samples where insulin cfDNA is undetected. Finally, purified cfDNA from recent onset T1D patients yielded a high signal for demethylated amylin cfDNA when compared with matched healthy controls. These findings support the use of demethylated amylin cfDNA for detection of β-cell-derived DNA. When utilized in conjunction with insulin, this latest assay provides a comprehensive multi-gene approach for the detection of β-cell loss.

Effect of Caesalpinia bonduc Polyphenol Extract on Alloxan-Induced Diabetic Rats in Attenuating Hyperglycemia by Upregulating Insulin Secretion and Inhibiting JNK Signaling Pathway

“…So amylin level could be considered as important target for the regeneration of β cells and treatment of diabetes. This argument is based on the fact that increased amylin level is connected with the apoptosis of β cells [51]. However, CPP extract considerably reversed the serum amylin level in treated groups.…”

Biomarkers of β-Cell Stress and Death in Type 1 Diabetes

“…The potential for other β-cell-specific genes (e.g., IAPP ) was recently demonstrated [38]. With emerging data on whole genome methylation sequencing, it should be possible to identify new, perhaps more specific, methylated and unmethylated CpGs in β-cells in an unbiased manner without consideration of gene expression patterns.…”

Epigenetic Regulation in Etiology of Type 1 Diabetes Mellitus

“…Studies were found increased levels of unmethylated preproinsulin DNA in peripheral blood samples of patients with new-onset T1DM compared with controls [37,38]. However, although this hypothesis has been disputed, circulating demethylated amylin DNA has seemed to be a valid biomarker for β-cell death in T1DM [39].…”