Elevations in Circulating Extracellular Vesicle Mir-21 As a Biomarker of Developing Type 1 Diabetes Mellitus

Presentation Number: OR12-6
Date of Presentation: April 4th, 2017

Alexander Lakhter1, Farooq Syed1, Bernhard Maier1, Raghavendra G Mirmira2, Carmella Evans-Molina3 and Emily Kristen Sims*4
1Indiana University School of Medicine, 2Indiana Univ Sch of Medicine, Indianapolis, IN, 3Indiana University School of Medicine, Indianapolis, IN, 4Indiana University Scool of Medicine, Indianapolis, IN

Abstract

Early detection of developing Type 1 Diabetes (T1D), before widespread destruction of β cell mass, is needed for improved outcomes of T1D prevention strategies. MicroRNAs (miRNAs) released in extracellular vesicles (EVs) have been proposed as ideal biomarkers due to their stability and feasibility of detection. Previous work from our lab demonstrated that β cell miR-21 production is induced by inflammation, and RT-qPCR analysis of diabetic NOD mouse islets revealed a ~4-fold increase in miR-21 expression compared to NOR controls. We hypothesized that the inflammatory milieu of developing T1D may also increase miR-21 in β cell EV cargo. EVs released by INS-1 β cells exposed to a cytokine mix of IL-1β, INFγ, and TNFα were isolated using ExoQuick reagent. RT-qPCR revealed an 8-fold increase in EV miR-21. Similarly, a 5-fold increase in miR-21 content was observed in EVs from cytokine-treated human islets. Nanoparticle tracking analysis of INS-1 and islet EVs showed no changes in EV quantity or size distribution in response to cytokine exposure, implicating transcript upregulation and changes in EV cargo as responsible for the increase. To assay changes in circulating EV miR-21, we performed longitudinal serum collections on NOD mice and insulitis resistant NOR controls, from 9 wks of age and until diabetes onset (defined as blood glucose > 200 mg/dL x 2, n=7). Starting 3 wks prior to diabetes onset, EV miR-21 levels progressively increased in serum of diabetic NODs compared to age-matched NOR controls, peaking at a 10-fold increase from baseline levels. To validate relevance to human diabetes, serum EV miR-21 was assayed in samples collected from pediatric T1D patients at the time of diagnosis, as well as age-matched healthy controls (n=19/group). Consistent with our NOD data, serum EV miR-21 was significantly increased in diabetic samples compared to controls. We propose that EV miR-21 may be a promising marker of insulitis and developing T1D in susceptible individuals. Ongoing studies will further define relationships between EV miR-21 content and β cell inflammation and death.

 

Nothing to Disclose: AL, FS, BM, RGM, CE, EKS