Combined Analysis of GAD65, miR-375, and Unmethylated Insulin DNA Following Islet Transplantation in Patients With T1D

• Published in: The journal of clinical endocrinology and metabolism Vol. 104; no. 2; pp. 451 - 460
• Main Authors: Roels, Sarah, Costa, Olivier R, Tersey, Sarah A, Stangé, Geert, De Smet, Dieter, Balti, Eric V, Gillard, Pieter, Keymeulen, Bart, Ling, Zhidong, Pipeleers, Daniel G, Gorus, Frans K, Mirmira, Raghavendra G, Martens, Geert A
• Format: Journal Article
• Language: English
• Published: Washington, DC Endocrine Society 01.02.2019; Copyright Oxford University Press; Oxford University Press
• Subjects: Adult; Autoantibodies; Beta cells; Biomarkers; Biopsy; Cell death; Clinical s; Deoxyribonucleic acid; Diabetes Mellitus, Type 1 - surgery; DNA; DNA Methylation; Follow-Up Studies; Glutamate decarboxylase; Glutamate Decarboxylase - blood; Graft Rejection - blood; Graft Rejection - diagnosis; Humans; Insulin; Insulin - blood; Insulin - genetics; Islet cells; Islets of Langerhans Transplantation - adverse effects; MicroRNAs - blood; Middle Aged; Pancreas; Pancreatic islet transplantation; Postoperative Period; Prognosis
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2017-02520

Abstract Aim Several biomarkers have been proposed to detect pancreatic β cell destruction in vivo but so far have not been compared for sensitivity and significance. Methods We used islet transplantation as a model to compare plasma concentrations of miR-375, 65-kDa subunit of glutamate decarboxylase (GAD65), and unmethylated insulin DNA, measured at subpicomolar sensitivity, and study their discharge kinetics, power for outcome prediction, and detection of graft loss during follow-up. Results At 60 minutes after transplantation, GAD65 and miR-375 consistently showed near-equimolar and correlated increases proportional to the number of implanted β cells. GAD65 and miR-375 showed comparable power to predict poor graft outcome at 2 months, with areas under the curve of 0.833 and 0.771, respectively (P = 0.53). Using receiver operating characteristic analysis, we defined likelihood ratios (LRs) for rationally selected result intervals. In GADA-negative recipients (n = 28), GAD65 <4.5 pmol/L (LR = 0.15) and >12.2 pmol/L (LR = ∞) predicted good and poor outcomes, respectively. miR-375 could be used in all recipients irrespective of GAD65 autoantibody status (n = 46), with levels <1.4 pmol/L (LR = 0.14) or >7.6 pmol/L (LR = 9.53) as dual thresholds. The posttransplant surge of unmethylated insulin DNA was inconsistent and unrelated to outcome. Combined measurement of these three biomarkers was also tested as liquid biopsy for β cell death during 2-month follow-up; incidental surges of GAD65, miR-375, and (un)methylated insulin DNA, alone or combined, were confidently detected but could not be related to outcome. Conclusions GAD65 and miR-375 performed equally well in quantifying early graft destruction and predicting graft outcome, outperforming unmethylated insulin DNA. The diagnostic potential to detect occult β cell loss in both the acute and chronic phases after islet transplantation was compared for three chemically distinct β cell selective biomarkers.